Well I don't know a whole lot about either machine, but I think you have to ask yourself what applications will you use the equiptment for? For me, I want to play live and play along with sequences stored on 3.5 diskette. I like a good piano sound, I like good strings, warms pads.... stuff that will be mellow mainly and warm. I don't get into techo much at all. I'm trying to learn about the XP-50 myself. I think I see either an xp-50 or an xp-60 in my future. Or I'll hold out for a 128 polyphony machine.
Best wishes
RW