I, for one, am proud of Portnoy for following his personal goals and not just his pocketbook. Having said that, there are many sides to the same story. I can also understand that the band members had very different personal feelings about what they wanted to do. While Portnoy might have felt drained and exhausted (probably because it sounds like he is a workaholic), Petrucci and the guys may have felt that they were on a roll and couldn't afford to lose the opportunity to keep on driving. I fault neither side for their decisions. The fact that it's put a personal rift between them is the real shame. But once again, there are many sides. It's fairly clear to me that Portnoy is a really difficult man sometimes, he's the most controlling, and possibly quite aggressive, socially. The guys may have been quietly sick of it.
He mentions Roger Waters and David Gilmour. Waters was a right asshole towards the end of his stay with Pink Floyd. He was throwing his weight around far more than any band leader should ever do, making the band a solo project, firing members for no good reason, snubbing people: media, fans, and band mates alike. It was time for him to leave. And whatever you think of Gilmour's revival (I personally love Momentary Lapse), he made it work. It's very possible that DT and Portnoy were similar, though there hasn't been nearly the control freakishness of Waters.
I'm starting to really warm up to the album more. On the Backs of Angles is really good, I've come to realize, and yes, it's got A LOT of similarities to Pull Me Under. However, I haven't heard any other I&W comparisons yet though.