The scene is set. Ahira...dead. Doria...catatonic. The rest of the surviving band... returned from our world to stand at the mercy of the Hand. In payment for returning Ahira to life, the Matriarch of the Healing Hand asks for specific payments from each. The most arguably substantial payment comes from Aristobulus/Lou Riccetti, in that he is required to give up his "Aristobulus-ness." To alter the scene so this price goes unpaid, we must examine this interaction. Why does the Matriarch ask for each individual form of payment from each Other-Sider?
My original perusal of the scene lead me to conclude that to accomplish the resurrection there seemed to be something necessary about the power Aristobulus holds, like electricity to run a defibrillator used on a heart attack victim. However, the scene actually boils down to improving each individual while preparing them to tailor-fit the design of Karl becoming the "Bane of all Slavers."
There are allusions that the Matriarch is something of a godlike being. Subtly included is her possible omniscience: she seems to see the destiny at hand for each member of the party, and uses that knowledge to give them something to contribute to Karl’s cause. Either this adds up to her wisdom coupled with the knowledge Ellegon supplied, or it may be a supernatural ability. For purposes of this argument, let us say it is the latter.
Given this level of perception, the Matriarch’s motivation seems selfish in that a morally good religious leader (deity?) manipulates outsiders—although in an ostensibly positive way—to a crusade (ending slavery) she sets off while keeping the overall "smoking gun" out of her tabernacle. Accepting this semi-selfish motivation, we can conclude Riccetti lost the Aristobulus aspect of himself to force him to be the engineer, both civil and technological. Given this presumption, we must slightly change the motivations of the Matriarch to rationalize the change in her required payment (stripping the magical ability from Lou Riccetti).
Rather than solely motivated to end slavery, let us say she additionally wishes to leave the scientific progress in her slice of the multiverse untainted. The Hand’s proclivity for preservation shows itself in the history of their compound: the pristine tabernacle on a nature preserve in the middle of a magically destroyed wasteland. Perhaps the Matriarch, if similarly inclined to preserve the natural progression of cultural development, might have taken a different tack.
Keep the above argument in mind when considering the following: as an alternative to "dewizarding" Lou Riccetti, suppose the Matriarch instead removes all engineering information from Aristobulus’s mind. To clarify: Lou stays the venerable wizard type, but his mind, in regards to modern science, becomes blunted or fuzzy while keeping his personality and memories intact. Think of it as a selective, spiritual lobotomy or perhaps, more accurately, induced amnesia. This is almost a backwards version of what happened to Riccetti, as we learn in The Silver Crown (Lou remembers what it is like to be a wizard and uses this understanding to persuade Karl).
This gives a twist to the long-term story, even putting a damper on the six-guns mixed with sorcery. Referring back to the scene in the tabernacle, Aristobulus could have made good on what he began to suggest before the Matriarch interrupted him. I quote, "...I’m not the one who’s wanted in Pandathaway—now I can go back, and qualify for the guild, and—..." At this point, the Matriarch cut him off. We can only speculate as to what else he would have said, but we can assume from the cocaine-like addictive compulsion of the mystic arts in Gaurdians of the Flame stories, Ari’ would have made good on the beginning of his promise. Loyalty not withstanding, he would pine for the Library of Pandathaway, leaving immediately. Alternatively, perhaps later he could infiltrate as a spy for Home, assuming the rest of this scene continues without much change and Karl agrees to fight slavery; but all of this looks perhaps too far ahead in the time line, so let us speak more in the immediate.
Let us consider how there being more Aristobulus and less Riccetti affects the short term. The subsequent diversion from the storyline caused by this change truly shows in the opening action of The Sword and the Chain. Ahira and Karl have the, "Riccetti is going to be a problem," conversation, then Karl goes gallivanting off to kill four swordsmen. Ari’ had nine spells listed in The Sleeping Dragon (the short names being Sleep, Lightning, Fire, Glow Temporarily, the two-way version of Charm, Injure, Preserve, Shatter Metal, and Dispel Magic), none of which seem to intuitively apply to this situation tactically; besides Andy-Andy’s response seems to have worked fine. Perhaps he could have slung a spell at the last rider that shot Karl in the back, which would have made it difficult to use him as a messenger later. Beyond that, Dr. Deighton supplied Ari’ and Andrea each with a spell book as he returned them to the alternate universe. Perhaps within that time, they could have either exchanged some spells or Ari’ might have done a quick study of his book to gain some spell more pertinent to attacking men on horseback. We will never know. At least there would have been one more combatant and one less college student hanging around camp.
After this action-oriented scene, Karl and Walter find themselves on a shopping trip turned slave raid. With Ari’ around rather than a defenseless Lou, it is very plausible that Ahira would have sent the wizard instead of Karl. Karl picks fights, Karl has a price on his head, and Karl can be a subtle as a train wreck. All reasons to send the now mostly "native" Aristobulus to do the haggling. The whole dynamic of the story would have changed had this happened. At this point, the Other-Siders were at a relative standstill, pondering the question, "well, what-do-we-do-now?" The remedy to this came with the addition of major supporting characters: Karl recognizes Chak on the slave block, frees him, and then Chak plays a part in the freeing of Alia, Kirah, Tennety, Fialt, and others. Coming across these individuals, especially Chak, lead to the move to the Therranji valley and the establishment of the Home colony, so for the sake of consistency let us stick with the idea that Karl and Slovotsky did the shopping.
Even assuming Karl and Walter did leave the wizard behind at the tabernacle to, say, catch up on his reading, other aspects of the story would have to mold to this new reality. First, the valley that later would be called Home would change. Ari' probably would come up with magical defenses (along with the Spider sect’s wards) for their new home, rather than marvels of logic and engineering. Home still occurs, but it would grow more like a traditional squatters’ village: starting with tents, then perhaps advancing to some sort of native construction style rather than emulating a fort out of our Old West. Perhaps one of the natives might have known enough to help construct some of these details such as a mill, possibly some rough fences, but they would have been much cruder. The party would not possess the knowledge for the creosoting of timbers on the palisade, let alone been able to build it efficiently. Combining Ellegon’s help, the wood knife, and the Other-Siders' cultural knowledge, a palisade might happen with instead of black-coated timbers, magically "Preserved" ones. There would have been no water wheel, no indoor plumbing, nor any other "modern conveniences." While inconvenient, this does not make-or-break the story.
Second, there is the magical scrying device held by Ahrmin. Perhaps a J classed wizard such as Ari’ might have some innate ability to sense spells of detection aimed at those around him. This information might have made Karl more cautious on his trip, knowing that someone specific was deliberately showing interest in his movements.
The next question: would Ari’ leave with Karl on his trip to Melawei since, as he said, there was no price on his head?
Let us say he did. The confrontation at the inn with Baron Furnael would have gone a far different way, especially if Ari’ had taken the time to study the Invisibility spell from Andy-Andy. A confrontation with the baronial wizard could have become messy, or it might have settled the issue more quickly without as much drama. The specific details in that scene do not affect this outcome. Much more pertinently, Ari’s presence would change the danger level in Melawei. If one assumes wizards learn spells in a similar way, the slavers’ wizard would have to be equal or better than Ari’. Ahrmin noted the Slaver’s wizard having Fire and Lightning in his repertoire. This would make him similar to Ari’ (see above), again noting that Ari’ may have learned a trick or two from the Deighton-supplied spell book. In addition, the wizard himself said he could dim his magical aura as to be less visible to the Mel wizards. This statement might make him superior in that Andy-Andy noted that while sleeping, "...it was easy to see Aristobulus’ (aura) glowing strongly, a few hundred feet away, blazing in the night like a red beacon." TSD Chapter 12. One way or the other, a powerful wizard along to fight slavers might have meant the survival of Rahff Furnael, maybe the death of Ahrmin, and most definitely a "Karl-loyal" wizard (as opposed to Seigar Wohtansen) would have observed the sword of Arta Myrdhyn first hand and possibly explained some things.
On the other hand, let us say Ari’ stayed with the newly forming colony when Karl left for Melawei. Would he be there when the raiding team returned several months of misadventure later? No. Over a years time he would eventually strike out on his own. As with real world addictions, he would pursue his vice: magical power. This likely decision would make the need for Karl and Slovotsky to get back on the road (Chapter 18, The Sword and the Chain) all the more immediate. They would have to hunt down Aristobulus and figure out what in the hell he was doing, perhaps in a similar vein to the story of Jason and Mikyn in The Road Home.
In conclusion, if Riccetti had kept the Aristobulus persona, he would become a factor in the immediate storyline instead of making him some degree of secondary catalyst to allow ideas from our reality to find fruition in the fantastic world that is Guardians of the Flame. This would not necessarily better the character or for that matter the overall story, but it definitely would introduce some interesting possibilities. The flavor of the fiction would change. Change the flow of the mighty ocean with one single pebble thrown at a different angle? In this case, definitely, but not for the good.