Given cheethamhill's findings, I wonder if the "single production buff" means "single building", rather than "+100%" that we were all assuming. ie it will work on Aunt Irma, Rainbow, Red Flying etc as they work on single building, but not on say Kitty Lure, Efficient Traps etc, ie those with radius effect which work on multiple buildings?
Presumably it wouldn't work on Christmas Market buffed buildings either then, but hopefully the barracks boost WILL stack with Skunk and Training Grounds.
Hopefully the Dev Diary will clarify, but I suspect given past performance it will be cryptic/vague and we'll have to discover the full mechanics by buying/using. If BB are reading this, perhaps it would be wise to include examples of each attribute, ie say what will and won't stack etc.