Just a small improvement: Would be nice if renoise remembered the octave your virtual keyboard was in the last time you used it (i.e. when reloading renoise). Alternatively the ability to set the default octave yourself, I would find useful.
Remembered another option I thought about before:
The ability to hear samples as they are when you play them (i.e. optional button in diskop), bypassing the current DSPs of the track you are in. I would find this useful when loading new samples without having to go to a track free of DSPs first to hear them as they are.