Oh yes they are...they bought the original PA without knowing there was an upgrade coming...that was just a nice perk, and a necessary one for Korg to supply, since Yamaha's SA and Mega technology was making the Korg sound rather plain and and dull.

Contrary to what you seem to believe, modules aren't that much less expensive to make than a full keyboard arranger...in fact, they charged quite a bit for the RA-series back in the day.

In my opinion, they were more trouble than they were worth, especially for someone on a busy gigging schedule, that was setting up and tearing down a lot.

Tone modules are much easier to integrate than arranger modules....if I was to add anything, it would just be a tone module, and trigger it from my arranger.

I'm already more than pleased with Yamaha's factory styles and their great 3rd party support.