First thing, congrats on megadrum! Just finished the basic parts of megadrum, very impressed, cheers man!
Just a suggestion, which I dont think would be too hard to implement, on channel 1 you have an input for a potentiometer? On other inputs, the choices are Piezo/Switch for pads, why not add an option to accept input from a potentiometer rather than a pad, that could then output a midi CC instead of a midi note? I thought that this could be used for, say an expression pedal linked to a VST effect, or would effectively allow the user to create any kind of progressive control?
I know for me, personally, this would have a wide range of uses, I would maybe even consider building a second megadrum to handle progressive inputs

Please let me know if i'm way off with this idea, but im assuming it wouldnt be too hard as the code has already been written for hi-hat controller!
ohawker