The BK-9 is a great arranger in many respects, but marketed dismally. The two screens are a put off until you bother to read the manual to understand that they act in concert to one another in making changes much faster than menu based buttons.

The only peeve I have is that Roland was too lazy or cheap to hone their sounds, unlike Yamaha e.g. that has polished their OOTB sounds.

It is definitely a keeper IMO, but takes a bit of work.