Hmm. Most of these bands have been ripping off the earlier, and superior, purveyors of the metal/hardcore crossover bands like Cave In (pre Jupiter), Himsa, Converge, Coalesce and Shai Hulud. I have no particular issue with this metalcore genre when it's done right, but like melodic death and symphonic black metal, the genre is over-saturated and now all the crap is going mainstream. Not to mention one of the guys in Atreyu dissed heavy metal and said Green Day was more important to him musically, so he can basically die, given their style is blatant In Flames worship with some whiny wanna-be Cave In vocal stylings.
As for Darkest Hour, their older stuff was not very emo, just brutal deathmetal/hardcore and I don't mean melo-death. more importantly, they're incredibly cool guys. The vocalist and guitarist played pool against myself and a friend during the Crown/Darkest Hour tour and they're METAL fans. Slayer, The Crown, Morbid Angel, etc. Though i did get into a bit of a brawl with some fuckhead "straight edge" types during their set because they were trying to ninja pit and I kind of threw one of them into a wall and a half dozen of them tried to jump me. Unfortunately for them, the bouncers in the bars were all college football players and people I knew, so they got beat about a bit, and thrown out of the show.