The current pre-release of the client ("pioneer" in the version) is only compatible to itself. So you can only play with other testers. Please be aware!
I would love to know the win/loss stats on games where there's a match up between a team with two lower rated players and one player 300 pointrs stronger than everyone on the opposition.
My suspicion is that the stronger player pwns all.... Though that might just be at around my own level where that happens.