John,

I have a PA2X-Pro and for a while was tempted to buy the PA-900, mainly because had found a demo model at a very tempting price (1350 euros), but -even considering the 128 voices of polyphony, the new styles with four fills and some new DNC sounds- the overall sound quality wouldn't be on the same level and so it would actually be a downgrade.
At this point I prefer to wait, also because there are rumours of a PA3X successor maybe at winter NAMM; otherwise I could upgrade to a PA3X-76 (here too there are demo models, for sale at 2400 euros).