Eh, I hate to double post, but I have an entirely unrelated controversial metal opinion that I feel the need to express...
Agalloch is pretty much the least metal thing of all-time. I mean, not literally, but they're by far the least metal band that I've ever heard out of bands that are called metal. Less so than AC/DC, Led Zeppelin, Nirvana... Granted I am ONLY judging from The Mantle since that is the only one I have.
But I'm listening to it right now and... The Mantle is a great fucking album. No doubt about it, I love it. It's a great fucking album that lies somewhere inbetween indie rock and post-rock... and nowhere near metal. Okay, so most of these 10 minute songs have one or two 10 second bits of black metal styled vocals, and if you strung all of these parts from the album together, you would have a few minutes worth of a very kickass crossover between indie rock and black metal. But even in that case, it's not pure metal, the instrumentation is perfect to support the vocals, but it's still rock instrumentation. And the rest of the music, don't even joke. Since when has folk strumming and ambient beats become metal? Is Neutral Milk Hotel metal now because they made ambient tracks like Burzum did? There's really no connection, even if Agalloch is metal-inspired, the music they play has virtually no metal in it. Seriously, if VERY SPARCE use of harsh vocals, alongside an entire album of non-metal music and clean vocals... if that's what counts for metal, then nobody could ever claim that Atreyu isn't metal. And no, I don't think Atreyu is metal. But if a tin bit of harsh vocals for seconds out of epic songs make something metal, every metalcore band must be kvlt.
And don't get me wrong, I totally love this album. And I adore the little bits of obvious metal influence that comes shinning through in their instrumentation. It's awesome. But it's an influence worthy of crossover status at best. And even if I were to concede most of my points, and say that The Mantle has a lot of metal on it... even so, there are only a few metal songs on the album, with the rest being definitively indie rock or post-rock.
I know ya'll likely have a low opinion of my opinion on metal, but even so you can surely see where I'm coming from. It is surely the result of some bizzarre mistake that Agalloch has ever been considered a metal band.
I'm fully willing to believe that they may have had other more metal albums (Ashes Against The Grain, perhaps?). And I'm also even willing to believe that they count as metal, but if so then I think they should be credited with deeply broadening the scope of what can be considered metal, because the instrumentation on The Mantle is so blatantly rock. And it's not like you can connect it back to Judas Priest or anything like that. Some of the techniques might also be used in metal, but in a different way. The Mantle clearly uses them in the definitive indie/post-rock way. I honestly have to say that the main reason people (in general) would ever consider Agalloch metal is because that's the scene they're in and that's what they're called. You could have that exact same stuff coming from a band in the indie scene and of course it wouldn't be called metal.
Just my 2 cents, peace.