For me keybed quality is #1, and it will be under the SX-900 as a lower manual, so physical size issues are important. I will bring the SX right down on top of it and I will have slightly tilted down and overhanging keys, just like the Yamaha Organ I had. Not in a hurry so I will test them at Sweetwater this summer when I go to visit family. (I lived 10 minutes from Sweetwater, that was way cool!). The Roland A800 and one of the novations is waht I an thinking about. It HAS to have real MIDI out as well. I will not need any controllers on it.