In my opinion, the yamaha has better acoustic sounds, guitars, strings, pianos flutes saxes in pretty much every category really except the drums. But the korg has far more editing capabilities and has far more assignable features than the Yamaha.

From what you have said the yamaha would seem to be the way to go.

By the way i own the Korg PA1X but would never swap it but i more than likely use my instrument differently than you would use yours.