Based on this video...I preferred the darker piano on the 900..
I thought the other sounds on the 950 were a bit lifeless..no punch..The 900 seemed fatter but they were swimming in effects..
If the player owned both of these keyboards..I would sell the black one..
My advice ..sell the silver one too  

That BK9 is looking better everyday..  

The biggest  plus with the 900 is the touch screen...Why Yamaha hasn't figured this out yet  

And Roland would have hit a home run if it had a touch screen...makes me glad I own what I own  
 BTW: Korg is still too synthy sounding to me....