This is one of those mods that kart just doesn't function without, and I love how you put your reasoning for each cvar on this page. It does a lot to make the game feel less janky, and even makes Shrink, humanity's first sin, almost bearable.
However there are a few I have some grievances with in practice.
Extended flashtics are long, like really long, and vanilla flashtics practically don't exist. I wish you could set how long the flashtics are directly on a server by server basis.
Growth bump still applies bump force to the grown player, which has gotten me or others killed in several circumstances while in grow and colliding with someone. There is no worse feeling than bumping someone with a power item, and you're the one who dies. Mid-air at least, grow should just either act as a star or at least not apply bump force to the grown player. Maybe even just make them a 20 weight for collisions or something, anything that makes getting pushed into a pit less likely.
I am not sure if this is like a mod conflict or something since I don't even know if it happens consistently, but extended Hyudoro seems to not have offroad immunity at some arbitrary point during the Hyuu. Either there should be an indication to where the offroad immunity ends if this is intentional, or fixed if it isn't.
Really good addon with just the Bumpspark and Haste tweaks alone, which makes out-speeding SPBs as a heavyweight on spirals possible, and makes acceleration characters more viable, respectively.
In addition, the other tweaks are really good to tap into: Extended Flashtics and Orbital Limit are so ingrained into lots of custom servers that it might as well just be vanilla. Respawn Points is the icing in the cake, even if there's a few edge cages where it leads you into death. Even the Shrink tweaks can make it a lot more tolerable.
Pretty much a must in any server even if you're willing to use one or two of the settings.