Do we actually have any idea what Mangini writing might mean? First off, what roles can he play? I know when Portnoy left, there was a lot of "Well, Portnoy did a lot, but it was mostly just his parts and some vocal melodies"--does Mangini have the same limitations? And what style does he prefer? Just because he can be really technical doesn't mean he will be--JP can be really technical, but he wrote BTS, for instance. I know Mangini's pre-DT work was mostly on a session/intermittent basis, so is there really much of a body of work out there that someone can point to and say "Here's what he can do?"
I'm certainly very excited that he'll be contributing, as I think DT functions best when everybody contributes and is inspired, but the information doesn't really push me in a concrete direction yet.