1) Edit all layers (except locked ones) in relative and absolute mode.
2) Mix control for synth insert effects.
3) Voice cycling mode, like on the Oberheim multi-voices, where each new note goes to the next available engine.
4) Possibly a ringmod insert effect, ideally with controls for frequency, keyfollow, mix , and waveshape. I don't know why but I think ringmod will be gorgeous in this synth.
5) Ability to change the colour of the GUI would be MIND-BLOWING, but now we're probably just getting into fantasy land... Even if it's a simple hue filter, imagine being able to make it look like a red 101



