I wouldn't go so far to say the S900 is a mini Tyros2, but it is a great keyboard based on it's own merits.
It does have many of the fine SA voices of the Tyros2, but it doesn't have the same keyboard/keybed so it doesn't have aftertouch.
I have a PSR-3000 as well, and I think the S900 is a substantial upgrade from the 3k, although others may have different opinions.
The audio to USB device on the S900 is a great feature, and the S900 is actually less expensive than the 3k was when it was introduced.
Ian
------------------
Common misconception...size and weight equal quality and performance. Don't be fooled.
_________________________
Yamaha Tyros4, Yamaha MS-60S Powered Monitors(2), Yamaha CS-01, Yamaha TQ-5, Yamaha PSR-S775.