@LaurentB thank you for your deep thought on this matter and laying everything out in such detail and clarity.
Regarding the Next Part command while recording: I agree. We will disable mixer access with a long hold while recording so this can be on the downpress.
Regarding the undo/redo/re-recording issue, the main debate I see is, do we want:
3 levels of undo, with 3rd level being a complete ‘clear track’:
Advantage: Keeps redo hands free
Disadvantage: You must wait until the 3rd level of clear track to have an accurate ‘re-record’ (more time) – and this may cause frustration in users who are not aware of the necessity of the clear track for an accurate re-record.
Redo is a touchscreen only command - you touch the waveform to redo:
Advantage: all re-recording is on the downpress at all times. Everything is more consistent.
Disadvantage: you have to bend down and touch the screen for the redo command.
I am personally leaning towards @LaurentB’s suggestion of redo as a touchscreen command because I think redo is a rare situation where you did undo by accident. My only hesitation is that quantized mode users do not have the re-record timing problem at all because everything is cued at the end of the measure and they won’t like having the redo command relegated to the touchscreen.
I do not want to make the system work differently in quantized mode and freeform mode because that would cause massive complexity and likely cause many bugs as the modes diverge in operating procedures.
If anyone has any other suggestions to solve this problem, I would love to hear them.
Otherwise, we will probably go with @LaurentB’s suggestion of redo as a touchscreen (and MIDI) command.