I was curious about the Nott M7. I like his M6, but in the first movement, I hear a kind of hissing sound. I don't know if the conductor was vocalizing or if something else was going on, and I didn't notice it in the other movements. Also, I find the recording lacking in deep bass, and string tone is dull.
Barenboim almost always annoys me, and so far I can't get past the first movement of his M7. Mahler almost always writes with a strong rhythmic profile, which Barenboim tends to smear. When he left the CSO and said he would never conduct it again, I thought, OK, it's safe to go downtown again.
I'll say this for Haitink: He knows how to "scale" a live performance in a way that reduces the acoustic problems at Orchestra Hall. By comparison, I heard Barenboim do M9 there, and because of the insensitive conducting and uniformly gray sonic sludge, it was one of very few concerts that made me want to leave early.