Yes John, Casio has mastered acoustic piano sounds quite well... I think they sound great..

However, brass, woods, strings, guitars and such are a whole different department then piano's as they can be played with much more different articulations ... A piano is allways a hammer falling on a snare. But a guitar for example can be picked, slapped etc etc.. And thats where SA2 technollogy comes into play... yamaha did never see the need to add an SA2 piano model...

Only the future will tell us...