@Horsa, my friend, I put here a video to provoke your conceptions about singing and (heavy) music.
First, a preamble:
The video bellow is from a second fiddle heavy metal band (technically is "power metal" actually), which have some songs I really like, but is, well, seen as too "soft" by orthodox heavy metal fans. But it will surely sound (in this song, at some passages), extremely heavy for your ears.
But since you know (and like) a lot about singing, I ask you to try to turn off your biases a bit (everyone has them, endure the heavier parts while paying attention to the vocalist. Technically, the guy is unbelievable. And he flirts a lot with what is called "dirty" singing, but pay attention to how much different things he accomplishes here, either from a technical or from a pure "interpretation" point of view. My point here is that you can really, really enlarge the "sing properly" concept:
BTW I think
@Chris Koziarz will enjoy it.