Nah, I woudn't need anything so complex. Hmm.. I'll try an analogy.
A looping reel of tape. Obviously you can affect the pitch of stuff by using a dial or simply grabbing the reel while recording. And likewise, backwards could be accomplished by flipping the reel over. That kind of control.. but I must clarify, I only would want one loop total. The overdubbing could be on top of the main loop in its entirety, such as the line 6, or you could overdub a small section of the main loop, while keeping everything else on the loop the same.
Recording of the knob gestures I think, would not need to be a virtual process, rather, would just affect the audio from the loop (once it got around to that section again). I would like a pitch and key control.. since I see that alot on digital gear nowadays, but to be perfectly honest just the pitch control would do.
And no, I'm not opposed to this being done in software.. it's just that I have all kinds of PC software that can do all kinds of processing, but I always go back to trying new things in the Line 6.
The click thing probably would be an issue.. I wasn't even thinking that technically about it until now. But I wanna emphasize that it need not be a seperate loop in synch with the main one, but more as a way to just to plain ol' overdubbing onto a smaller area.. like a skipping record.
Whew.. now I'm confused!
Ah yes, this is a tricky one, because when you stop looping the sub-loop an d go back to a longer loop, you might end up with clicks at the edges of the sub-loop. I have been trying to solve that problem with little crossfades at either end of the sub-loop, but I want to be able to keep playing the larger loop while recording into the sub-loop also, and haven't quite figured out how to keep the crossfades perfect at all times. I was ready to bail on this feature but it's cool to hear that someone else has thought it would be useful, so I'll try and get back into it.