I have no particular opinion on FM. The only thing that worries me is like you say: if klystrack starts doing too much, it'll start being less oldschool/chippy and more of a DAW-ish thing.
I totally agree but I think 2op FM still falls pretty much into the oldschool/chippy area.
Also.. instead of converting some FX busses to 'masters', you should just let every instrument export to all FX busses. You just toggle which busses it sends to... like [ ]1 [ ] 2 [ ] 3 [ ] 4 etc. That way people can make their own, and as many master channels as they want, and it also opens the door for some creative FX work.
Seconded!
And a simple live mode. Load two songs side by side, each with a volume fader. That's it
Allso agreed, hotkeys for channel muting would be nice if we are talking live mode too.