Regardless of piano sounds, the Casio is the only keyboard that has three sensors in the key mechanism. This usually comes in just over $1000 digital pianos made by Kawai, Roland, and Yamaha. I think Kawai has one under $1000 model that has tri-sensor action. According to Casio:

this enables key movements to be measured precisely. A note can be pressed more than once without the key having to return completely to its starting position. The "tri-sensor" design enables even the most sophisticated of playing techniques to be achieved.

...and here is the KETRON GP1 with the new AJAMSONIC Piano Sounds ... also notice the EDITED GRAND within the video that shows the user can EDIT sounds on the GP1:- http://www.ajamsonic.com/ajgp1.html



Here, the GP1 is used to control the Midjay PRO which shows how versatile the Midjay PRO is - hook it up to any Midi controller and obtain similar/better results:- http://www.youtube.com/watch?v=DDEFYANj58k

Thanks