I remember there are some who have used both the Roland Bk-7m and the BK-9. I am a BK-7m owner.
What's your impression regarding the difference in the range of sounds? From the tone lists I can tell that the complete BK-7m is inside the BK-9, plus lots of sounds from the Sonic Cell (which is from 2007), a few others (unfortunately not many from the SRX boards) and the 22 SuperNatural ones.
All in all, would you say the BK-7m already covers all really important sounds, or is the BK-9 an entirely different experience soundwise from your point of view?