I'll be playing with my (Bob Sellon-modded) PCM42 tonight. If you don't have answers by tomorrow, I'll post my findings. But right off the bat, I suspect (some of) your questions refer to the PCM42's Sample mode (which I never use), not the echo/delay mode. Is this so? And you wrote:
>When the unit is in Repeat mode, are you able to change the delay tap? If so, what happens to the material in the loop as you press the Inc/Dec buttons?
"Delay tap" being delay time? There is no "tap tempo" function on my PCM42.
>If the feedback level is set to produce multiple echoes, and you put the unit in Repeat mode, is the recycling audio captured into the loop, or just the incoming audio without the echoes?
By "Repeat" I assume you mean "infinite repeat." When you put it in this mode, it "freezes" whatever has been created up to that point, echoes and all. I love this: build up a huge texture, freeze it, and solo 'till blue in the face. I'll experiment to answer your other questions.
Douglas Baldwin, coyote-at-large