I haven't actually tried either one. Although I guess eventually I'll have to upgrade. I'm still using a Roland GR800 with a GR808 guitar that I got in the mid 1980's. Works great except for the occasional tracking problems.
From what I hear, the newer synths tracks a lot faster and you don't get as many glitches in your midi recordings. (a constant hassle since you have to go back and edit out all the accidental short notes and quantize everything.