When I used the Windows version with Yamaha Motif Rack, to obtain the right brushes map,
I did the following manipulation : Prefs / Arrange (2nd button) / Drum Brushes / XG format note #s
( instead of GM/GS patch 41 )

Does an equivalent option exist in the Mac version ?
Thanks

Hello,

No, however you should be able to accomplish it by changing a couple of the notes in the drum map dialog (MIDI menu | Edit drum kit). Trying changing note 38 to 25, and note 39 to 27, and then save the drum kit so you can load it whenever needed. For reference, those notes are listed at the bottom of this page:
http://www.pgmusic.com/tutorial_gm.htm

But what about simply loading one of the GX compatible "Synth Kits", like the XG.DK, instead of the default GM Kit? As far as I can tell by reading the info on these (such as the PSR kits), doing this should include the correct GX layout for the drums as well as the GX patches. Or am I wrong in that?