My thoughts about buying a new keyboard.
1-I owned the Technics kn1000 through the Kn7000.
2-Psr 2000, Psr 2100, Tyros 3, Psr 975, and now the Sx900.
Other than a SD card that was added to the Kn7000, I have not seen a large difference on the new models being offered. So why do I buy the new model?
I heard it said here – to keep up with the new technology. When I compare the Psr2100 to the Sx900, wow, night and day difference. Since Technics is no longer, I have done the same with Korg and Yamaha. The only reason I bought a Sx900 is because my needs have changed.
Price: If you stay with the same model each year, Psr 2000 then the Psr2100, the price of upgrading is small considering the excitement, and learning you received. The only guy I know is Gary, he is way ahead of the dollar game.

John C.
PS, I just recieved a Sx900, I made the right decision.