A simple sequencer/arpegiator would be of great use, but I would suggest that the clocking mechanism is separated into one module that would allow the zynth to act as a MIDI master clock. So the clock element would have tempo tap and external lock to allow it to locked to an external master clock source.
I would also employ one of the spare 1/0 ports on the all in one board as a LED that could display beat.
One feature I’ve always found to be a missing element is the ability to not only add notes to an arpegiator but to be able to transpose a sustained arpeggio. Thus one can change key. It’s not difficult to patch up but you end up with two keyboards (one to arpeggiate, one to transpose) which always seems wasteful. To make it a mode switch on the arpeggiator interface would seem easy and useful.
I wouldn’t move volume from the top left. It’s a zynth standard.
Is there an already existing bit of jack based goodness out there…?
Absolutely, to the zynth world it’s just a MIDI rule away…
The real debate is how would we tie it into the extincting infrastructure. ON which menu do we keep MIDI tools? Because you are also effectively in the world of MIDI file playback as well, or so I would feel if I was coming to the device as the disinterested user.
Anything that reduces the clobber you take to perform is a bonus, I try not to allow myself more than I can take on a bike!
so One keyboard over two !