Well, in my experience with BF3 abd 4, DLC is always populated, always full. Didn't play BC2 DLC ,so don't know about that, but BF3 premium was my best PSN purchase ever. In fact, DLC maps in BF3 were much much better than the vanilla maps !
It seems the same with BF4. I have bought only Naval Strike, this time around, there has never been a case where I couldn't find a game.
Not interested in Dragons teeth , though, as it is made by Danger CLose and not DICE. I love the way DICE makes maps. No other game's maps feel like real places , except DICE. Nothing feels "set-up" or placed there for the sake of the game. THe objects, their scale and placement, all look completely real. Can't see that quality in Dragon's Teeth from the video I saw. The DICE touch seems missing.