We can try to make the stealth mode be less strong on ice/snow levels may be, although it's not simple. I don't think changing the size slightly is a problem, currently its only make the player around 25% taller or smaller (and is not changing the collision behaviour).
The tiles motion blur things can be interesting, although the effects are more interesting if you can impress other people with them
I remember that there was some interesting effect on some playerworlds where you are seeing player motion blur (transparent copy of yourself displayed behind you).