For my part, while I do ultimately like the Saiyaman stuff as it is (especially in the anime, where I agree that it gets a bit more room to breathe and indulge in the concept more) I also definitely, if I'm being totally honest, wouldn't have been that fond of it at all if Saiyaman did in fact end up being the main direction that DB ended up taking for its final arc overall. It just wouldn't have meshed at all with Dragon Ball in general and felt way, way too disconnected, like an idea for a whole entirely different and unrelated manga that Toriyama awkwardly stapled onto Dragon Ball because there wasn't room enough in his schedule to do both. Plus I largely overall love the Boo saga as-is in general to begin with, warts and all. As it stands though, I'm totally fine with Saiyaman as a fun little short-lived diversion and transitional dovetail into the next arc.
In all honesty, my only real issue with the whole Saiyaman bit (manga or anime) is that Gohan never gets an actual, full-blown supervillain to face. A supervillain of a more classically Toriyama/Slumpian gag-oriented sort that is at least, both to match the general tone as well as to not suck too much of the air away from the main storyline to come. That lack of a costumed arch-enemy for Saiyaman feels like the one vital missing piece of the picture, as Saiyaman is (to put it mildly) hardly the sort of superhero who particularly screams Daredevil/Punisher/Batman-esque vigilante with a primary focus on street crime. He definitely needed some kind of ridiculous, silly costumed nemesis with superpowers and/or some absurd scheme for global dominance.
Hey, maybe Toriyama could've somehow brought back and worked in Pilaf to fulfill that role!
I definitely agree though that the schizophrenic nature of the Boo arc is where the seams really start to show in both Toriyama's improvisational approach to writing/drawing the series as well as in his general burnout with having worked on it week in and week out nonstop for almost a decade by that point. I also think that this is also why the anime for it is the one time where it feels like a genuine IMPROVEMENT over the manga, as what felt like rushed beats in the manga are given more breathing space in the anime (it also helps that the animation quality took a HUGE quantum leap forward after some pretty bad on and off lows during the Cell arc).
I will say this much though: on a fresh, first time-ever experience following it week to week/month to month in its original run, the Boo arc's constant zigzagging legitimately worked to its advantage. It lent the whole arc this anarchic, unpredictable "anything can happen" sort of feel, especially early on. Even with the benefit of time, hindsight, and being able to look at the whole thing finished, I'm still genuinely left surprised as to how well the whole thing still hangs together overall.
Its definitely more rickety and less tightly focused than earlier arcs, but not so much that it ever seriously torpedoes things. Gohan in general is really the biggest casualty of the arc's more pronounced than usual seat-of-its-pants nature, due to him being such a blatantly and constantly dropped thread: first as Saiyaman, then as Goku's successor against Boo. But that aside, the lion's share of it overall generally works astoundingly well; oftentimes in spite of itself, and definitely in no small part to Toriyama's natural gifts as both a comic artist and an idea man. Its chaotic as hell, but juuuuuuuuust controlled enough and executed with enough raw skill (however frayed around the edges from exhaustion) to generally hold together as a fun and suspenseful romp.
In a lot of ways, the Boo arc in general is the Dragon Ball equivalent to Marvel vs Capcom 2: totally thrown together wildly at the spur of the moment without the slightest hint of restraint or regard for inhibition: but done so by raw talent that's still skillful enough so that even at its sloppiest it still yields something that's genuinely a keeper... even if it feels at times like its only being just about barely held together with superglue and scotch tape.
