Metal had reached its furthest perimeter, and has since retreated a considerable distance. Nowadays, its fascination with the dark side, as the Rev Mann identifies, rarely extends to outright devil-worship, providing instead a healthy rite of passage for teenagers and colourful entertainment for a more seasoned demographic.
This is somewhat true. Bands don't take things further than the stage these days, it's not so much a way of life as it was for Varg and friends.
Yet whether Christianity really can learn anything from heavy metal, as the Rev Mann also suggests, is another matter. Speaking as a fan of 30-odd years, it never taught me much, except to enjoy a good riff, have a good time and suffer the consequences.
Christianity could learn just as much from William Blake. And it seems to me the long-time fans (20+ years) always take metal the most lightly, which could mean either age or burnout for the others. It would be interesting to do a 'where are they now?' survey on all the older DLA bands, or at least what they are listening to.