+1 to possibility to display flats in Key Editor and everywhere else - as well as controlling whether sharps or flats are shown with key signature markers in Event Display. It’d make things clearer when working in diatonic paradigm.
In addition to that, +1 to possibility to use custom note names (for things like numeric pitch class notation) and perhaps a 12-pitch staff. Would be very interesting to try working in numeric pitch class paradigm and see where it leads.