John,
Good review! You took the words out of my mouth. I play styles, they all sound excellent. I do use a few midi files and I like what I hear when playing them back. I just picked my SX900 yesterday and am very impressed with the keyboard, the keybed is a step up too. I love the way it mimics the Genos OS.
Dave, I second what Randy wrote. The s970 is one fine arranger, this SX900 takes it up a few notches.