For me personally I has not been so much an issue of the sound quality as it has been of the pressing quality. In fact, sound quality wise I have to say all heavy metal vinyl pressings I have heard have sounded better than their CD counterparts. For example, Metallica "Death Magnetic" and Audioslave "Audioslave" are horribly compressed on the CD versions (as a side note, both are produced by Rick Rubin whose phenomenon I cannot understand as every record he produces sounds just awful in the CD version; how he maintains demand for his services is a sad telling of what sound sells these days.); however, both records sound much, much better on vinyl. But the quality of Metallica pressings on the Because Sound Matters label is just shit. Burnt vinyl, distortion throughout the songs, vinyl noise right out of the sleeve as if it's been played 500 times. Disgusting. The Dutch pressing of Audioslave is way better. So I'm still an advocate of hard rock and metal on vinyl in general, but the quality of the pressings needs to improve big time. If they press on cheap vinyl with no concern for the quality, no matter how good the sound might be otherwise, the record will never sound good.
