I have both and was happy with the BK7M soundwise. With the FC7 pedal it worked quite well. I bought a 61 key controller leyboard for it and beside the cables that Don mentioned made a great lightweight setup. Only used it out once for a job and it did fine. Then I grabbed a deal on the new BK9. That has a lor more to offer and its all in one at a fantastic weight . I still use the BK7M at home with my Casio Privia. Good for practice on a weighted keyboard.
Both are great units and soundwise either will do a good job.