The proof is in the use!!
I have a multi setup for that purpose, for when I am trialling new smf songs.
It responds to ALL midi commands and works exactly as a GM module should.
I do not use the GM setup for shows as I have other multis for them using higher bank sounds.
Now, without putting words into hi mouth, I suspect Phil was perhaps trying to say the Motif line, and by extension the racks, are not GM sound modules, and he is correct they are not, and they are not setup to be so. But they ARE GM compatible and will respond as I have previously stated when setup for that purpose.