Hi Frans,
before you dash out & buy a Roland, why not try a demo version of One Man Band or Live Styler. You could use your PA500 as a soundsource & controller. There's heaps of yammie styles floating around, they will probably need a bit of editing, but not as much work as trying to actually convert just say a yammie style to korg. Even though you'd need to do a bit of tweaking & maybe fix up some of the drums, you don't have the additional work required to get them working correctly in the korg itself.

It might give you a rough idea as to whether you actually would enjoy using a software arranger as a second keyboard.

Dan's software compared to just OMB, does have the benefit of a suggested soundsource (sd2) & arranger software combination.

best wishes
Rikki