In my opinion @thetechnobear did already a better suggestion;-)
octave change feedback
musical layouts do not change (visually) when you change octave, so currently there is no visual feedback when you hit +/-
as a minimum, Id like to see the +/- light when you press them for some feedback
(they do have a positive click, but still visual reinforcement is useful)
perhaps later, also some way to colour different octaves on key/drum pad elements?