I hope Nigel doesn't mind me referring to another forum. Your question is answered by this post on Korg Forums:
http://www.korgforums.com/forum/phpbb2/v...2471f520780cfd8

Here are a couple of direct links to the comparison chart referenced in the post:
https://imgur.com/dgHYU9P
https://imgur.com/krVzZPW

Obviously the PA1000 dominates both of these. I've heard some impressive demos of the PA700, and I seem to recall that the PA900's keybed came in for some criticism, although I'm not sure improvements were made with transition to the next generation.