I doubt, if the KMA OS is such a PITA, that the PA500's is going to be significantly different...

But it all boils down to the styles. The worst arranger in the world, if it were the ONLY one that had the sort of styles you want, would have to be your natural choice. Porting a bunch of styles over from another manufacturer to whatever you get is going to be hit and miss at best, and a major endeavor on top. Not to mention, Latin ones are usually the hardest ones to port, as inconsistent as each manufacturer's Latin Percussion drum sections are.

The trouble is that Latin styles have such an utterly different meaning in different countries... Do you want Mexican Latin, Cuban Latin, Brazilian Latin, Central American Latin? All quite different, often with the same names.

As always, it boils down to the styles. Is ANYONE making exactly what you want?