I don't find them "darker" per se, bassier yes.
Love the instrument separation and it is definitely up there with the 1840 and HD600. Very clear as well, but as I mentioned I liken them more to the 840s but more refined. ;-)
I haven't had the 1840s in months so maybe members with both at the moment might provide more detail.
I'm rocking mine right now.
Listening in Shuffle mode as usual. Genres I listen to: Emo, Pop, Punk, Metalcore, Salsa, Merengue, Hip Hop, Trance, House and Reggaeton. ;-)
Too bad you don't have the Sony 7520 to compare it to :)