So let me see if I understand this:
-it's based around a looper that does not degrade volume
– there are several desirable features, including pitch/time shifting and simple time shifting, a filter, reverse mode and some sort of modulation
-these must not overwrite the loop
Well, playing around with the TF's looper, it is possible to achieve some of this:
– The time/pitch shifting is possible. Record your loop at say 1x. Then playing back, set the Depth knob to smooth. Then play around with the speed knob – it'll change gradually as you turn it. As far as being non-destructive, if you go back to 1x it'll sound exactly the same.
– With regard to the rest of your ideas, I can see the benefit of modulation and reverse. Perhaps in v2?