If you haven't visited it, there is a motif forum at http://www.motifator.com
where you might find the answers you are looking for. The MM6/MM8 are really PSR series keyboards. You can edit the on board sounds but cannot create new sounds or download new sounds into these boards. The midi ports have limited function. The MM6 is 61 keys and has synth action--non weighted keys. The MM8 is 88 keys and has yamaha's GHS action--what you find on a P-85, YPG 635. It's lightly weighted keys. While these have some nice sounds, they are not genuine motifs and have 32 note polyphony. You would be better off looking at the MO6/MO8 if you want a good synth. You could consider the used market as these are quite well made.