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!