The Multi pads are a bit more solid under your finger, almost all of the controls feel better and firmer (in my opinion) as far as Multi pad notes are concerned I believe that it's based on maximum number of notes for all of the multi pads combined, much like a sequencer. I could be wrong I've never really looked into it because my use is fairly limited to a couple of things. I'll look further. If you have a 550 I have a midi file I can send you of a song I'm just finishing that features the sweet flute. let me know if you'd like it and if you want add to it or modify it, let's see what we can come up with.