Diki,
Many times I played Roland E50 and E80 side by side, and they do sound a little different using the same sounds. However, sometimes I found myself preferring the E50. It is set up better out of the box, with fewer editing options on the overall sound and parts. I'm convinced the E80 would have to sound better if set up exactly the same.
If the E80 were only half the weight . . . it would have saved me lots of money when I sold it! It is a killer keyboard though.
DonM