I just tried this mod out and I have to say, you did an amazing job with it overall! Well, at least from what I've tried so far.
Things I like the most and wish were in the vanilla game:
* Fang's bouncing is SO MUCH more fun when it doesn't reset momentum. It feels very stiff and awkward that bouncing around as him comes at the cost of momentum resets and therefore is difficult for speedrunning, and it feels amazing to have that reset done away with.
* Metal Sonic being able to run through spikes no matter what alleviates the issue that his race and battle don't faithfully show what he's like as a playable character.
* The attraction shield is SO MUCH more fun to use when it's chainable and I don't think it takes away challenge factor at all. It's not like this is mindless button mashing; you have to aim the camera appropriately each time to continue the chain, which makes it rewarding when you are able to continue chains.
* The armageddon shield turning into the ash shield fixes my big problem with it (after you deliberately use it, you're vulnerable all over again) and I like the visual detail of leaving small poofs of ashes behind.
* The force shield redirecting momentum is a great change too and makes it so much more interesting. In my experience, the elemental and force shields' vanilla abilities are just "fast fall" and "slow fall" in practice respectively, which I'm not a fan of. I can see your version of the force shield being very useful in scenarios where you're right about to fall over a hazard or death pit, but then remember you can use the shield to redirect your momentum somewhere safer.
* The bubble shield's momentum reset is a good riddance too, it's now way more fun. In this mod, the crazy interactions with slopes aren't the big thing about the bubble shield for me, the elemental shield has that instead.
* Thank you for nerfing Tails' flight, he so badly needed a nerf.
Thoughts on Sonic's ability:
While I'm not the biggest fan of the idea of Sonic having his ability replaced with a double jump, I think this mod pulls that idea off very well. Having shield abilities usable after the arc jump is a genius idea that solves the issue of being redundant with the whirlwind shield, and it's also fun to pull off with the other shields. Though it trips me up that Sonic doesn't get instant bursts of speed in this mod, playing around with it has warmed me up to the idea of Sonic balancing speed and versatility, while leaving the insane instant speed that's difficult to control but fun once you master it to Metal Sonic. It almost feels like those two are swapped here, which is pretty reasonable.
Changes I would suggest:
* Say in Amy's character select screen blurb that unlike other characters, she uses jump+jump for shield abilities, and after that, say you can change that using console commands.
* Was it intentional that doing a shield jump+spin ability and then holding spin no longer sends you into a spin state? I'd personally prefer if that was kept in the game, if you don't want to land into a spin then just don't press spin.
* I don't think the bubble shield should be able to bounce on damaging grounds, or at the very least, not over lava.
* I think Fang's gun should be kept to killing most enemies in one hit. If you're really going to make the gun take multiple hits to destroy one-hit enemies, then at least put a stronger visual indicator that the enemies are weaker now. But I'd really rather keep the number of hits it takes to kill an enemy the same no matter how you do it.
* If most characters can spin onto horizontal springs and hammering on springs makes Amy spin as well, then where does that leave Fang? It feels odd for him to be the only one who can't make good use of horizontal springs, but I can't think of how he'd have a good way to spin from horizontal springs. Maybe somehow work that into his tail bounce?
