I had a psr970 and went to an SX900, playing much of the same music genre. I really like the new OS after getting used to it, and I put my old registrations on a thumb drive, beside my primary. When I feel a particular style from the 970 is better suited to a song, I tweek it with the new machine, and save it in my primary User folders. I do think that it would be a mistake, however, to slide everything over from the prior boards without thoroughly auditioning a comparable native equivalent style.
However you choose to do it, I agree that using an SX900 and supplying legacy styles, as needed, would be a win win situation.
Bernie
_________________________
pa4X 76 ,SX900, Hammond SK1, Ketron SD40,Ketron Event X Centerpoint Space Station, Bose compact