Just read an S900 review, add in a few SA2 voices and a bit better display, you've probably pretty much got it

My take would be that those SA/SA2 voices are WELL worth the upgrade at this point. They are, IMO, the main reason Yamaha rule the roost in those mid-price arranger markets...

To be honest, this one (S910) is starting to get my juices flowing. It might be time for me, at least for my home studio, to add in those Mega guitar patterns and SA/SA2 voices to my palette...

I am still unconvinced I could integrate the G70 and the Yamaha sufficient for it not to be a major PITA on a live gig, but those Mega and SA voices keep beckoning...