sk880user "PSR740 (which I own) with PSR9000PRO and motif and I have found no significant difference in sound quality despite the utter insistence of other users.
"

do this:
call up standard drums, monitor in stereo.

bring up Dance Kits on all three keyboards.

call up piano,

call up synth sounds...

If you can't tell a difference, hmmmmmmmmmmm...

PSR9000Pro will be closer to 740, but MOTIF does sound different.