I never had any trouble swapping from my grand piano to the 740 and back again. There's a difference of around half an inch over five octaves. Feels just the same to me apart from the bungy action on the PSR. Maybe that's UD's problem - the crappy action on the PSR. The keys are a one piece plastic molding, fixed at one end, and relying on the natural springiness of the plastic. Talk about cheap.

Bryan