Getting back on topic...
I have the GameCube version here. Framerate is perfect, and the pixel-shader effects for the water and other fluids work nicely. Only problem is in the special stage, where it slows down when lots of mines explode. Also, 2P mode runs at a constant reduced framerate, most definately because of the second camera view.
About the movement: I have never seen my character move abnormally through a loop or a conveyor. The movement is still pretty bad (Which is the fault of the core engine), but you'll be happy to know that you can't get killed because you go flying through an object or the camera messes up.
If there's one thing I dislike about the camera, it's that when you use L and R or the C stick to rotate the camera, it zooms in so that you can't see as much, and you have to move your characters around for, like, 20 seconds without moving the camera before it finally zooms out again. However, I've never noticed the camera reversing on me. Never.