Hello,

With a bad back, I'm not sure you'd want to lug around a Pa1X. However, it is a great keyboard and, with your prior experience with the Korg way of doing things, it would be a good fit for you.

On upgrades and such, loungelyzard is right on the money and Korg are very good at issuing upgrades on a regular basis. Re. the Pa1X boards, there is one about to come on stream about which you can find some lively discussion at the following link:
http://www.korgforums.com/forum/phpBB2/viewtopic.php?t=13290

In fact, Tramannoni (Paolo) on that forum is employed by Korg Italy and is a regular conduit for ideas and suggestions put forward by forum members. I think he has also popped up from time to time in this forum, too.

Good luck with your choice.