Hi Goran,
Yes I hooked up a BK7m to my Korg Kronos 88 and felt the sounds blended in very well together. Sometimes I used my Kronos for the lead sounds and the BK7m for the drum patterns and baseline for on-the-fly playing and composing). I eventually sold the BK because I felt the pattern buttons were too few, with too few available variations overall (i.e. less fills/variations than a full arranger KB), and their placement limitations within the BK housing being too tight (easy to hit an adjacent button by mistake) and a bit too far away from my Kronos keybed to be easily reached. Below is a link to the Kronos/BK7m setup I had showing it being used for a song I wrote at the time. I had decided that, if I liked the BK7m enough, I would buy the foot switch for it, but subsequently decided that, overall, I would prefer a dedicated arranger like the Korg Pa3x76. I particularly like the layout of the pattern trigger buttons on the Pa3x. To my fingers, and playing style, the buttons are very accessible and easy to trigger on the fly. Since I would prefer to have easy random access to patterns on-the-fly, I decided to sell the BK and wait for the Pa4x to come out (i'm hoping in the next 12 months). I figure such a dedicated arranger will give me the most convenient pattern/style access. The Pa would also make a nice second tier keyboard. And you could still connect your Kronos/M3 or Fantom to a full arranger like the Pa to get access to all sounds of both. Here's the link to the Kronos and BK being used together:

http://youtu.be/jkxpeT7L5Lo