Definately the PA1X can play PA 800 styles that were done pre version 1.02 and it does so well. There are more effects in the PA800 and so in some cases the wrong effects are in the styles but absolutelty for the majority of styles they work very well on the PA1X

Paolo Tramannoni who is a product manager for Korg Italy said

'With Pa1X, you can load Styles made with Pa800 v. 1.0x. You cannot load Styles made (or edited) with Pa800 v.1.5 or Pa2X (any version).
The new Style format includes a Guitar track, that would make no sense in Pa1X. Therefore, these Styles cannot be loaded.

Best regards,
Paolo'

And here is a link to all the styles on the Pa800 pre 1.02 version. I have them all on my PA1X hardrive
http://www.korgforums.com/forum/phpBB2/viewtopic.php?t=30370