I thought generally it worked. I think the game got confused with clans and parties, i.e. it would only check the party leader allowing members of the party without dlc through the net. I'm just guessing based on what I saw and read on here.
Personally I can see the need for dlc to keep the game fresh, but I'd just prefer them to add £15 to the price of the game and give everyone the dlc when it comes out.