For the styles, the difference in sounds plays a smaller role of course. The arrangements are largely the same. For the acoustic guitars in the styles I think there is a difference, even if the BK-9 doesn't makes use of the SN-A guitars as style parts, but it has better acoustic guitars in the ordinary PCM sounds, too.

I just prepared a short live Beethoven symphonic orchestra demo with my BK-9 - the BK-9 sounds amazingly good here, and this is where the BK-7m would be dramatically worse.