I am an owner of GEM Sk880 and I have tested PSR9000PRO. In my very humble opinion, GEM Sk880 beats PSR9000PRO in every category except the following:

1) some selected sounds such as: sweet trumpet, sweet flute, and few others. The piano on PSR9000PRO sounded ok but not that great. It is sad that they ported that same piano sound to Yamaha Motif.

2) The fact that PSR9000PRO had ballad styles that I really liked.

But otherwise, I am very disappointed.

But one of the biggest surprises is PSR740. My brother bought one and it included the same identical nice ballad styles as the PSR9000PRO and it also included the sweet trumpet and sweet flute sound. So the best of PSR9000PRO is included in PSR740 for merely $800. If you think that I am biased, search around. I initially was upset about PSR740 but after comparing it to PSR9000PRO, I realise the extreme value of it.

Now I am not saying that GEM SK/WK series is the best. They are outdated but certainly PSR9000PRO cannot beat them (at least not in every category). I have not listened to VA7, PA80 or SD1 because there is no dealer in my whole city that carries a SINGLE ONE. So I do not know.