I have mixed feelings on the whole thing. While I wasn't completely happy with the metal direction that the last 2 albums were taking (especially the pseudo-cookie monster vocals), I still enjoyed the albums a lot (BCaSL more so, SC less so). And while I'm glad that DT's still continuing to release albums, there's still something missing. While JP and JR were the main source of raw musical ideas, MP helped arrange them besides his own ideas. I also think it was good having him there in a leadership role alongside JP, instead of JP just directing everything on his own now. It's also a bit of a bummer that MM feels that he can't suggest all the ideas he has when writing, which I think stifles the creativity of the writing and perhaps taking the band into some new directions that they hadn't gone before (which is one of the benefits of having a change in the lineup).
With everything MP's done since, for me it's been a mixed bag - while I enjoy Transatlantic, Flying Colors, PSMS and to a lesser degree The Winery Dogs, none of them is anywhere near as appealing to me as DT has been. Nevermind all the extras that MP brought to the table for the fans (official bootlegs, rotating setlists, covers, regular contact/updates, etc). Lastly, I'm sad to see the relationships that he had with the other band members (save JR) breakdown - while that aspect doesn't affect me personally, I do know how it feels to lose a friendship with someone I used to be close to for many years and how I miss them, even if we've both moved on with our lives.
Just to clarify regarding what MP proposed regarding the hiatus, originally it was to be indefinite. When pushed for a specific amount of time (from the other guys), MP suggested 5 years. When that was met with resistance, he suggested 3 years, then 2 years, then 1.5 years, then 1 year and finally suggested them to use a temporary replacement for the next album/tour cycle - all of which were rejected. He was given the ultimatum of going with them into the studio that following January or leaving the band. This is my own personal speculation, but had MP originally suggested a smaller amount of time, like 1 to 2 years, maybe they would've been more willing to consider. But I can imagine them worrying that at the end of the agreed upon hiatus, he might not be ready to return to DT and may have pushed for more time (thereby getting his original wish) - if that were the case, I can't say I blame them.
I do hope that one day they'll be able to patch things up at least personally. But I do hope that one day MP will be back with DT again. I'm not holding my breath for it to happen, nor do I expect it to (unlike when the breakup first happen), but it is merely a wish I have.