I've owned both, and although the GP looked better, IMO it rode like crap, slow out of the hole, no mid range, no top end, and at all speeds except idle it porpoised like crazy, (fixable) it really was nothing more than a nice family cruising ski. and parts are extremely expensive for the 800's, they didn't make that many, and the same chit breaks every time so the parts you want are never cheap. (I sold mine for $200 less than I paid for it and only had it for 2 months, i was happy to get rid of the dam thing for a small loss)
I liked two things about the GP, it looks nice, and it had plenty of storage.
if it was a yami 701 i'd feel differently, same issues as the 800 as far as speed and such, but much easier to work on and parts are cheap and plentiful, but I think the biggest hull they put the 700's in was the XL models. I have owned the 700 and 760 XL's and I liked both for what they were, and my ride buddies liked me having it since they could each pack about 15 lbs of extra crap for me to put in the storage bins and it was easy to strap gas on the back too.