Still trust can be very tough online, does this mean only players with good friends can go for this type of game?, we know what some people can be like on this game and losing on purpose is what some people i'm sure you would agree would do in spite :p Especially if you bring tournaments into the question.
I'm not doubting the idea just raising a few issues that can be talked about, Maybe letting each pair play both players of the opposing pair other pair (resulting in something like a 3-1 win) would be quite a nice idea.
Things like ratings need to be taken into consideration too (would pairs of similar ratings only be allowed to stop a lower ranking having to play an opposing team in which one member wasa high rating?)
If there's solutions feel free to hurl them at me :p better to see problems of something before (or in this case if) it happened.