I didn't try the Yamaha, and I was set on the Casio for four reasons:

1. I read reviews that this was the best DP for under $1000 including a rave review in Keyboard Magazine.
2. The Yamaha acoustic grand piano is not my favorite.
3. The Casio uses high resolution MIDI to its internal sound engine and going out to any software that can interpret the 16,256 velocity levels as opposed to 127. I haven't heard if the Yamaha uses high resolution MIDI.
4. The Casio has the ivory style keys which I like.

But you do make me conscious that I didn't give Yamaha a fair shake. To tell the truth, I bought the Casio without playing it either. I had the PX-330, and I was unhappy with the quick decay in the mid-range. I heard that the PX-350 fixed this and delivered a much improved piano sound.