I have the S80 and it is really quite good in my limited opinion of synths. The pianos sound really good to me, as do some of the other sounds like some strings, and you can set the keyboard into many different zones so that one area can play one sound while another plays a different one, ie: piano and strings, etc. The keys are weighted but not graded hammer action. If you want an even more realistic feelin keyboard, I'd go with the P80...real nice feel, but not many different sounds. It's piano voices are really nice, too. I've played acoustic piano when I was younger for many years, then got away from the piano for about 20 years, and am just getting back into it. I think these two are good, and also the XV88, but it's also a lot more money than the other two. Hope this helps a bit.