Since you asked Chris, I'll join the crowd
This is going to be a live looper, and is likely to have some horsepower and interface possibilities beyond the basic, I'd suggest looking first to make the most comfortable live looping solution you can, then see what value/features you can add that would fit with what you've designed and offer something the other products don't as yet.
I'll toss out the idea of "States" or "Breadcrumbs". Basically being able to bookmark a particular range of memory and call it back with a CV and/or trigger. You could have your initial loop, perhaps two overdubs down the road you may want to save a state, later you completely change it up and wish to save that state, etc. There would likely be automatic states for undo and redo as well.
Going further perhaps the states would remember granular playback settings, and any other additional features that might be developed.
So you could have these different versions of your loop, be able to go back to them in any order, add to them, then revert, and maybe even set them to play back in an arbitrary order...
This isn't exactly slices, but more like a new level of flexibility with related loops.
Obviously this is dependent on memory, access speed, and how the heck you could design an interface that makes this easy and clear.