On the whole, I think this series of demos showcases the BK-9 the best I have heard so far.

http://www.youtube.com/user/LaPietradelParagone/videos

Really good players, using the BK-9 in live arranger mode, some using the Chord Sequencer, some using the audio loops. Plus some tutorials and demos of the iPad apps.
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An arranger is just a tool. What matters is what you build with it..!