I sell the Motif Rack and the QY100 (before this the MU models) and I can say that the Motif Rack is hands down the best sounding module Yamaha has ever made. 128 note polyphony, multiple outputs (6), USB, and only 1 rack space. For just under $1000.00 this is a great addition to any rig. If my memory serves me correctly, when you used the MU series as a tone module for individual sounds you could use user made sounds besides the XG sounds, but when in Multi Mode, you were forced to use XG sounds only and if you wanted to edit a sound in the Multi Mode, you were editing any sound you used in this part so if you made the trumpet have a brighter cutoff frequency, any other sound you might use in this part would have the same cutoff frequency. I didn't like this with the MU50 and MU100. Motif works like most pro modules allowing you to use any sound you've created or preset in a multi set up.
George Kaye
Kaye's Music Scene
Reseda, California