Hi.
I'd love it if one of the buttons on Push would act as a sustain button. I have two mini keyboards that have this function (M-Audio Keystation Mini 32 and Keith McMillen K-Board). How about if pressing SELECT would have this additional function? It's possible that I haven't thought this through enough, but it would be a nice function to have if you don't want to use a pedal.
The way this works on other controllers is: tap the sustain button with one or more keys pressed, tap sustain again to "release" notes.