Also as for the sliding, I have to agree with Hitm4n on this one. With the speed that the main character flies back and forth, if he were to suddenly stop, it just wouldn't look right (especially with the speed boost, believe me).
It probably would, but it would make the game play so much better, not having to take small steps all the time

Many platform games have a "ice world", where the character slides in order to force to the player to slow down, or have him fall into traps.
I think, it can be a fun challenge to undertake for a few levels, but for a whole game?
I would give up realism at any time for a responsive mode =)
I've attached a comparison of the Ruff sprite, old to new. I dunno, the Amiga video posted above was kinda squashed if that's what your comparing it to.
It is just now I realize how out of style Ruff is compared to all of the other graphics. The robots are extremely beautiful and the background are exceeding crisp, and then there's Ruff. It is almost as if the original was good at drawing robots and other dead things, and just gave up when he came to human.
But I can see the problem. How to make a human cute?