Casiobot...,
I didn't own the MO6..., BUT I did own the MO8. To tell you the truth 64 notes on the MO series is a really dogger. It doesn't take long to max the poly when sequencing. Here's the problem..., the MO6/8 have Motif ES sound engines. The ES's were designed to run on 128 note poly. The MO's run half that. So once you start to sequence on the MO's you'll really notice the poly limit.

With any synth the use of the arps..., and controllers such as the sustain pedal can be huge poly eaters. Take a synth whos sound engine is essentially the Motif ES.., cut that poly in half, use the arps and sustain in sequencing and BAM... POLY BLOWOUT.

If you're looking at the MO's primarily for PLAYING then the 64 notes isn't too bad.., but it will limit you in sequencing. For this reason alone I sold my MO8. I then later (after missing those ES sounds in my set-up) just purhcased a new Motif ES6 before the online retailers lost stock due to the XS's release.