I am quite familiar with all the operating systems of Korg, Roland, Ketron and Yamaha. They all have their strong points and weaknesses. Let me tell you though, the familiarity did not come over night (how about 25 years or so) and after doing a lot of work at home, I still learn something new almost every time I play, much of it on the job.
I think Roland has become a little harder with recent models. Yes, the USB has made things better, but as far as real-time control, the G70, E50, 60 and 80 were much easier. Main draw back with them was the method of introducing new files via the card, using dedicated folders.
I actually believe Yamaha has the clunkiest OS now. (I will now take cover behind something large and bullet-proof).
Anyway, Deane's post was not asking for advice as to how to do something, or whether he should keep the BK9, he as just letting us know that he was selling it because he preferred other options.
DonM