Avenged Sevenfold, top band. Probably one of my favs.
As for Metallica cover, no way. They've already done covers, and I feel it wasn't one of their strong points, I mean Walk? They pretty much did everything exactly the same? If I wanted to listen to something that sounded so much like the original I would listen to the original.
Anyway I can't wait to see how this new album sounds, I've already dl'ed the first single they released.