Depends on what you like to hear specifically in metal music.
Tyll Herstens has made a detailed review of the MDR-1R* (http://www.innerfidelity.com/content/solid-sony-mdr-1r-mdr-1rbt-and-mdr-1nc), even putting it on his "Wall of Fame" (http://www.innerfidelity.com/content/innerfidelitys-wall-fame-full-size-sealed) and that's what he had to say about the sound :
"Bass response is probably the biggest problem suffering from a lack of extension into the lowest octave and being a bit bloated in the mid-bass. The mid-range is good, but has a slightly emphasized upper-mid making the sound, especially of female vocals, present and forward, though pleasantly so. The treble is very well behaved delivering good clarity and very little, if any, treble harshness. Even though the top octave is a tad laid-back, the sense of space and audio image is surprisingly good. The balance between the bass, mids, and treble is pretty good and, though a little uneven, the overall impression is of a fairly well balanced sound."
Basically, you have a decent but slightlyy bloated bass, good mids emphasized in the upper range and great clear treble, with an overall smooth and fairly balanced sound. This could go relatively well with metal IMHO, if you are looking for a highly comfortable and portable set of headphone. It doesn't fail in any particular area and if you don't mind the slightly bloated bass and upper-mids, then for the price (199$ new) they are a good value.
Just to add, as I've listened to it myself, a music player with a good EQ can easily control the bloat - cut from anywhere between 80hz to 160hz, just experiment. However I don't think of it off the top of my head because it doesn't have enough space around my ears, although it feels a bit wider around the earlobes than the Focal Spirit One (maybe the angled drivers make a bit more space out from the head). My ears aren't even that big or angled outwards for someone my height (5'7").