Is Black Sabbath metal? I think it's rather the precursor, which for convenience I'll call hard rock.
I'm testing the Rhapsodio Supreme v3 right now. This has a newish, single MST driver. From what I understand, it's a hybrid driver of a DD fused with an EST tweeter, with the obvious goal of providing coherence, which it does in spades.
So I'm listening to some hard rock and metal on this right now to stick with the theme. And I've gotta say, with all of its issues, sound isn't one of them. It's doing Black Sabbath, Kiss, Aerosmith, Metallica, Disturbed, Tool, Perfect Circle, Nine inch Nails, all of it brilliantly with a darker tuning, great detail, and a huge soundstage. It's great with these genres!
Now if it were only a) less expensive ($6400!), and b) lighter, it's the biggest and heaviest iem I've ever tried.