You don't want the 9000 pro -- it has the same voices as the motif (PSR500, etc.)
If you really want those virtual acoustic voices, get a used MU100R module used for $400, this will actually give you an EXACT duplicate of the PSR9000 & pro, in a module. Of course being a module there are no styles included....
but...
If you can do without the virtual acoustic voices (and there's only six of them, in Korg land they are known as the EXB moss expansion board) and you do like keys rather than modules get the PSR740 board (same chipset as PSR9000 & pro minus the VL voices) yes it does have vocal harmony, used price around $500. And it has the typical (yawn) yamaha styles.
I'm not pushing yamaha arrangers by any means, just thought since you mentioned thinking about the 9000 pro you might like a cheap alternative to getting one.
Personally I'd go with the module. You'll have to go to ebay for a few weeks and keep your eyes open, the module is out of production but does show up occasionally.
As to choosing between the solton and korg PA80, isn't there $1000 difference between them? To me that's comparing apples to oranges. But I do see that for your needs they are the two top choices. I have a friend who's ordered the SD1, as a blind performer he bought a Roland VA76 and of course had to send it back, there was only that damned touch screen which did him no good. Now he's going for the Solton because of all the buttons -- he can memorize those. He currently gigs with a Roland XP60 and XV88 and "privately" has a PSR2000 (and doesn't care for it at all.)
I have a key/synth/module email group at
http://groups.yahoo.com/group/keyboard-synth-module-club/ if you are interested... we talk and also share songs. There's also MP3 storage for members (active members! only) at a companion site.
Me, I'm a home hobbyist only with a PSR740 backed up with a fabulous new Roland XV5050 module. My midi files and some MP3's (I am really bad about not converting!) are at
http://www.roncat.net/private.htm I love to talk synths, recording, etc......I have been playing keyboards since age of 3.
keyskitten aka "CATHY"