Hi,

GW-7 doesn't have built-in function for style editing. You have to use PC with EMC Style Works to edit. Or you can download many many Roland styles on net to use.
Beside this inconvenience, I think you will like its sounds (esp World sound groups). It has many new samples in comparison with other Roland keyboards.
However, if you afford PSR-3000, go for it. PSR-3000 has many functions for live performance althought its regular sounds (apart from Live!, Sweet!, Cool!, Megavoice) are not very impressive.
It depends on your ear taste.