So I own the Motif XF8, MOXF6, MOX6, and the MX49, and I haven't really noticed any difference in the overall organ sound in any of the keyboards that use the XF Samples (all of which I happen to own)
I haven't dug too deeply into the MX so it's possible that the presets are just edited better and have been tweaked to allow for the MX's more limited FX palette. However, I think the base samples are the all the same. (I could be wrong on this)
I've been wondering lately if adding a Ventilator would make using the Motif organs more fun, as one of the major limitations seems to be the Leslie. I think you would also need some sort of Vibrato/Chorus pedal (or you could just use the Yamaha onboard FX), and then you could just strip the Yamaha Voices down to the basic Elements (i.e., samples) and run them dry to the Vent and FX pedal(s).
Obviously wouldn't be a completely authentic Hammond experience but for basic pads and solos it might be adequate for cover bands, and one-offs.
Anyone tried this?