I have taken a chance, since I've got a few extra days off this week (Christmas have it's advantages...) and installed MC11 on the main media server. It's of course an install with an emergency exit, I have done a full image of the computer before I did it, and I have been so sneaky that I have not upgraded MC on the computer that has library management functions, since you can always convert a library backup for 10 to 11, but not vice versa.
But to my great horror there is a bad problem: When choosing a track from a search or the library, it will always go to the active zone and the control zone. It starts playing in the control zone, but not in the active zone! In the active zone either this nice, little box from MC comes up: "Please select files to play." Or it simply clears the current playing now, adds the track but doesn't start playing it.
This does not happen when choosing an album with a GAC scheme.