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.