Everyone has an off night. Petrucci is an incredible guitar player, but if you're going to play at the complexity level that Dream Theater plays at, there are going to be a few performances that are not as good as others.
As far as LaBrie goes, he turned in an excellent performance in Boston. I didn't hear any mistakes that were memorable enough to recall.
Well, I found a few ones, but they are going to be patched anyway. He had better nights in the tour (Manchester for example, or Philly), but he sounded great. Having listened to a lot of bootlegs from the leg I can tell that in Boston he pushed a little his performance beyond his standard confidence level, especially with regards to the highest end of the register, and that mostly turned out fine, but at least on one occasion his voice nearly left him in a critical moment. Still, a couple well aimed patches and this may very well become one of his best recorded performances.
Cool Annalysis, Wasteland, I notice these things in his voice too. It's cool when he gets one night to push it slightly more, so he hits more notes, but he uses proper technique so he doesn't blow out his middle voice passage and high notes.
Also he was AMAZING on the first show I ever saw of this tour (live, I hadn't watched youtube videos to compare yet), in Riverside. I think slightly better than the following night in LA. Still, Philly was probably even better, maybe Manchester.
I havent listened to the christmas CD in awhile, were there any mistakes in that?
The whole CD is completely and entirely untouched except Another Day, on which James was auto-tuned, or manually-tuned or whatever you call it when you tune something note by note. Either way it was a pretty quick job. They only had one performance of that to choose from.