Currently we can slice to a new midi track by time (bar, 1/2, 1/4, etc), by transient, and by warp points. It would be an interesting idea to create a midi rythm (aka groove) and slice based on that.
My idea is to get a sample, "convert to melody" and fix up the generated midi by hand (if needed), and then I want to slice the original sample based on the "note lengths" of the melody. So I would get a single slice for a tone, and I would get different lengths based on the source midi.