I've liked Dream Theater for a while now, and I think ToT is a great album. I don't see where this section is causing pain for people to listen to, I'm fine with it. It doesn't last long anyway. Besides, I don't listen to just the vocals, Labrie has never been a favorite of mine, I'm in it for the Myung/Petrucci combination. And Ruddess is awesome too.
ToT is deffinitely a step up from Six Degrees in my opinion, but I don't know if anything will ever top Awake and Metropolis Pt2. Awake had some nice heavy parts, and Metropolis had some fun rythms along with a good story to it. The only thing I'd like better about either of those would be if they got different vocalists for each character in the Metropolis story. I don't like James singing essentially four males and a female.
In short: ToT good, but not great... unless you're talking musicianship, they've still got it.