well, I am writing an essay about metal (music and culture) for graduation and I watched the movie and kinda copied that chart as well, but since I don't know all of the bands (honestly, that's a lot you're supposed to know) I just left most of them out. My intention in writing the essay was to show a relatively objective picture of the metal community and all the bands, but the more I wrote, the more I realized that you will always be bound to your preferences and what you know. I see that you put some bands in there as well, or did you take that out of some website? I wrote down all the bands and connections and you got some additional ones (COF, COB, e.g.). I won't put in the whole thing in my essay, but I described the different styles by referring to that chart, but I also added things and switched bands which I felt didn't fit in where they were. For example, I do not agree with the "fact" that glam metal was supposed to be over because I consider Wig Wam to be glam...but it's all just about opinions..I did even come to the conclusion that it's ridiculous to categorize everything because some of the bands change their style and some of them are just crossing the borders, so there's no way to put that right.
I think that Sam Dunn wanted to have the chart rather as a rough guideline without being totally guaranteed to be true. And if you want to do something good (what he really did because the movie is just awesome), you have to be really interested in what you're working with. And I know that I won't touch subgenres of metal where I don't know a lot simply because I couldn't stand in for what I write. I guess when we're looking at this chart, we should take it as an opinion that many people share. It's not said that it's accurate, but I think it resembles how the average metal fan would categorize what he listens to pretty well.
