A rock-opera double concept album. A dozen different vocalist playing aspects of the protagonists emotional state. Part of a 5-album post-apocalyptic science fiction epic (yeah, take that! Claudio Sanchez). A flute solo, a didgeridoo solo, and a bagpipe solo, FFS! What could possibly be more prog than that?
Oh, you want more twangly guitars?
Listen again. It took me 6 goes to "get" it.
I've had a bit of a listen to 0101100 (or whatever it's called). It's good, but maybe I just haven't listened to it enough, yet.
I found Arjen's work through Akerfedt's appearance on tHE, as I'm a bit of an Opeth fanboi. Am yet to plow further through the back catalog.