Take a good look at how ReCycle used to do audio loops... It would slice them, then give each slice its own MIDI note, so the MIDI file 'played' the loop, and this allowed you to do easy editing to reorder it if you wanted to mess with the groove.

But the icing on the cake was, it would take the last bit of the slice and timestretch it a bit, somehow... This allowed you to slow down the slices without gaps appearing in the sound. But something that needs to be thought about is, what do you do if you want TWO slices on any particular beat? No problem for a sampler or computer... just play them both. But if any system can't do this, you are going to have problems.

ReCycle was the granddaddy of loop slice and manipulation tools, and still to this day can do things few others can quite pull off. Give it a close look if you are considering allowing users to edit audio loops in the Ketron's....