As Bachus said, I sometimes use a BK-7m "on top of" a Yamaha MoXF. I haven't played arranger-based very often in the past years (more either completely live classical playing or in combination with self-made sequencer files), so I haven't optimized the integration of BK-7m and MoXF/Integra-7 yet (e.g. sending style parts to the MoXF via midi).
Generally, the two instruments are a very good combination. Even without complex midi networking, you can easily switch on and off individual live parts in the BK-7m and in the MoXF, so you are free to mix and combine any upper/lower parts of the MoXF and BK-7m range of sounds.
Of course, the BK-7m provides full control of sending midi signals also from each style track, so that e.g. a guitar pattern could be played by a MoXF guitar (if the MoXF is set to song/mixing mode). As I said, I haven't tried this yet, although one has to say that the acoustic guitars in the BK-7m are a rather weak point.
As you can store song settings conveniently in a performance list on USB stick, the necessary live operations like selecting songs, hitting start/stop and fill-in buttons are easily done. Editing on the BK-7m itself is not so convenient, I don't like the wheel too much, you have to press the wheel each time you select something, I think a sort of typist's neuritis can develop from it if you do it constantly.