In CC the platform behavior moved along ceiling slopes nice and smoothly. In C2 it uh..yeah..not so much ^^ I know the platform behavior is already super complicated but it'd be great to see this added! There are a number of spots in my game where it'd come in handy.
Another feature/option that'd be nice (might actually help the above) is to not force the player to fall when hitting a ceiling, but "push against" the ceiling until the whole jump has finished or the player lets go of the jump button. It's a somewhat uncommon mechanic but still useful depending on the game.