GM/2 is still the standard used for most mapping as it will work on anything, GS is quite common in studios and software as it was adapted by computer operating systems, however Yamaha have their own XG system (Which has been out as long as GS) which is why their voice layouts vary compared to GS. (Both GS & XG include GM mapping)

Yamaha biggest downfall is that they have to use special sounds (With their own unique articulations) in their styles to make them sound great, whereas every other manufacture can get great styles with just high quality sounds.

Personally the best style performance is with practically everything in the style turned off with the player imparting his own playing style on the performance.

Bill