Mike, sorry, but I need to clarify some of these points..

Firstly the Yamaha modules Motif, Motif ES and the Motif XS are FULLY GM1 and GM2 compatible and meet the full midi spec. (I own a Motif ES Rack).

What Yamaha have done is put BETTER sounds into the GM banks, but they still respond to the standard GM bank patches 0-127 as well as all controller and other GM requirements.

In some cases the sounds are even layered, not because Yamaha had to, but because they CHOSE to at the sample level, so users can get superb sounding SMF's even though they are still just the basice GM soundset.

There are several threads about the GM patches at the Motif Forums. And in particular Bad Mister (yeah thats his nick!!) has written several great explanations of this subject. (he is the, or one of the, chief Yamaha techs in the U.S.)

Personally, I always use the higher bank sounds as they have better efx and the ability for insertion effects.

Dennis