Just remember... (I think even Donny is a bit confused about this), audio loops played on the BK-9 do NOT follow your chords. They WILL follow your tempo and key changes, though. So no, this is not a Ketron!
If you prepare up audio files for specific songs with specific changes on them, then you can follow THEM with your LH chord changes, but if you've got a loop playing a Gm7 riff, you're not going to be able to have it change to a Gmaj7 riff simply by playing that in the LH. You'll need to record ANOTHER audio loop with the Gmaj7 riff...
For more general use rather than specific songs, you are much better off using the audio keys to play percussion loops, breakbeats, drum grooves, stuff like that. And with SEVEN of them available per Performance, you can add considerable variety to your style.
But sky's the limit if you are preparing them up for just one song.
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An arranger is just a tool. What matters is what you build with it..!