Yeah, if you don't like the PA 3x, I'm not sure why your interested in the 900.
Seems many people want the edditabillity of the Korgs and the sound of the Yamaha´s
The PA900 has the sopund engine of the PA3x, but misses some of the options, Styles and sounds are pretty much comparable soundwise...
The PSR950 has been available quite some time now, and you need to know there should be a replacement instrument probably by the end of the year...