Hi,
I have used my new CQ20B for a golspel choire (6 mics), solo Vocals (2 mics) and the Band (the other 8 mics/lines + both stereo inputs).
For mixing, it would have been very helpful to be able to form DCA groups for the choir and the band.
Mute groups are also very important, e.g. to quickly mute entire groups of microphones in the event of unwanted feedback.