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?

I used the BK7m for quite a while and liked it a lot. Primary reason for moving on was the number of peripheral devices I had to use with it. For example, external monitor for midi files, mixer and harmonizer, laptop for text files, keyboard controller and more, p;is extra power supplies and cables for all that,.
I tried the BK9 for about a month. I couldn't tell a difference in the sounds. It did have great organs that were probably better than the BK7m. Organs are not all that important to me, as long as they are usable.
I wish the BK9 had addressed a few of the things I've missed on Roland, such as no usable break/fill. It still didn't have vocal harmonizer. I didn't have a problem with the sounds though. My Bk9 required a LOT of set-up tweaking as out of the box it sounded quite dull. The quality is there, but you have to work for it a little.
It came close to being a keeper for me. I sure liked the weight!

Ditto

Thanks for your assessment.

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.

Thanks.
When I bought the BK-7m in 2011, I found generally it had a better sound range than the Fantom X derivates SonicCell and Juno Stage except for the strings and lacking expandibility with SRX boards. I also rated it slightly better than the Yamaha MoX I bought later (MoXF is much better though).
Now, as I own the MoXF AND the Integra, neither BK-7m nor BK-9 can create any excitement about the sounds, but still the BK-9 could be a very practical instrument with many reasonably good and a few very good sounds conveniently accessible together with styles (when I need them). I also like the chord sequencer feature to use the left hand for other things like manual bass.
Price at Thomann is still only 1,298 euros, probably not much time left for decision, then the last BK-9s might be gone. On the other hand I never wanted two full-size keyboards, and I'm not going to get rid of the MoXF.