I liked BK7m a lot. Once I programmed my controller (Edirol) with the free app, it was a cinch to operate. If you aren't a Roland user there is a learning curve though.
Only drawback to me was all the peripherals I had to carry --external screen for midi lyrics, external vocal processor/harmonizer/controller keyboard, pedal board, pedals, etc.
Having said all this, it was nice to have such complete control in live situations. You can access features from the midi controller that you can't get to directly from the module!