Me, if I was already most familiar with the PSR-3000, I'd take a serious look at either the S900, or maybe stretch your budget and look at a used T2. You will already be familiar with the OS, the styles you already use will be compatible, and there are a boatload of new styles that won't run well on the 3k...

Primary things that people fault the Korg's for are a lack of many user and third party styles (at least in comparison to Yamaha), a lack of fills (half of what the competition has), and in the PA500's case, no SA type technology (you would have to go up to the PA800 for that).

What style do you primarily play in?