I initially thought the documentary might just open up second guessing by fans, but this was wonderfully done and I definitely think it was a great choice to do this. Just being able to see the passion from Mangini makes me want him in Dream Theater and hope he's the last drummer they ever have. Portnoy coming back probably would upset me at this point.
Maybe I won't like the music direction, which is the real judge for fans on new band members. Even so, with the documentary I think they made their choice hard to complain about, and I wouldn't begrudge them for it.
Even without the landing the gig, I thought the auditions provided them all with nice exposure. If any of them didn't actually come off that positively, it's lost in the scope of the whole documentary. I'm definitely going to be checking out some music from a few of these guys I didn't know much about.