after such a long reply i can not say much...

i think s900 has some very nice voices, and if 76 keys is not a must for you, it might be better than e60 for you.
yes, roland has some features not found in yamahas (guitar mode, 6 fill-ins, d-beam, etc.) but if you don t really use those, go for more friendly s900 (it has multipads, vocalist, usb for pendrives, etc.)

the advice to check on both of them is probably the best one anyway.