This is one of the best Vanilla+ mods I ever used! I wish it was like this in the base game. There is a few suggestions I have in mind, though.
1. Give Sonic max control. (With the thok, insta-shield, drop dash, and peelout.)
2. Replace Amy's default spin with the hammer jump from SA1/Advance for special mobility. (Do keep the default spin dash, though!)
3. Allow Tails to fly again after fly cancel if he hits something.
4. Give metal a spam dash.
That's all I have in mind right now. Other than that, keep up the good work! :D