I'd be quite interested in whether any people have left MP.com just 'cause it's not a DT site any more. It used to be the de facto official DT boards, given that MP was synonymous with Dream Theater in many ways - he was definitely its mouthpiece. It was the biggest DT community, but you can't really call it one any more - especially not with the way they've ceased to allow discussion of JLB's projects, etc.
Which makes this the DT community!