I've commented on a lot of tangential topics in this thread, but regarding the article, I find the clustering really impressive. I know a lot of these bands and

I've commented on a lot of tangential topics in this thread, but regarding the article, I find the clustering really impressive. I know a lot of these bands and going by feel I broadly agree with a lot of the groupings. Perhaps it's not exhaustive or perfect, for example I would intuit Blind Guardian to be much closer to Demons & Wizards, because both of those bands share lyricists and themes, but the analysis otherwise nails many of the tuples. For example, Helloween - Gamma Ray - Masterplan or Edguy - Avantasia, where both groupings' bands shared lyricists. I also agree with other not-so-obvious groupings like Kamelot - Angra - Stratovarius or Falconer - Dream Evil - Hammerfall - Nocturnal Rites. Kudos to the author!