The BK7-M has 2 'Pianist Modes' that allow you to play normally.
The chords are recognized across the keyboard instead of just the left hand and it doesn't change chords until a minimum of three chord tones are played. This stops it from glitching on runs or melody lines. This feature was broken for awhile but was fixed in the recent firmware update v1.06.
I use mine at home for practice and coming up with song ideas, like a hardware version of Band in the Box. It can play backing tracks or record your playing the arranger functions to create your own track and then play over that.
It will play .wav, .mp3 and midi files. The best is to use midi files and edit them to your liking on a DAW such as Logic, Cubase etc. Then put them on a flash drive. You can get a lot of information from the Yahoo BK7-M user group
I would highly recommend if your doing a one man band gig with it you get an Roland FC-7
. It gives you hands-free control of seven dedicated functions, including start/stop and intro/ending.