I've yet to find any genre the HD600s don't do well. I listen to a lot of Tool, Chevelle, and Rock in general, and I have no complaints. I still have moments where my jaw just drops and I have to smile at how much fun I'm having. People say senns are usually laid back and have a...cough...cough...'veil' to the sound, but I have yet to find such a thing. I get impressive bass impact, beautiful mid range, and sweet treble. If I had to pick what this set up does well, or at least the HD600s, I would say guitars never sounded so clean, detailed, like an
actual guitar to put it bluntly. Also, I don't miss the massive bass of my DT 990s, as the HD600 does well in this department and I feel it's a more realistic amount of bass.
Back to your original question, yes this setup does Metal / Rock quite well for me, but I've always heard Grado rules in that department, a brand I have yet to delve into.