Let us know if you find a way to get the GM set for the S80 - I've also been looking for it on the Yamaha sites and haven't found it.

I'm not familiar with the Roland expansion system, but I haven't found the Yamaha plug in to be problematic. I installed the PF (piano) plug-in within 2-3 minutes.

Since you mentioned the Keyboard review - have you noticed the zipper noise he reported with the EQ knobs? I haven't.