I own the K2500, and in my experience, Kurzweil has always had a great sounding piano in its ROM. I havent yet heard the SP-88, but I have heard the Yamaha piano simualtions and to me they have always sounded overly metalic, tinny and over-processed. But everyones ear is different. But there are many others who agree with me so my suggestion would to defintely check out the SP-88 when it comes out. Kurzweil has never taken a step backwards when it comes to their products, so its safe to assume.