@Doctor J That’s fair. Metal is such a wide genre (like “rock” I guess), and I’m not familiar with the nomenclature, I was referring more to the sort of djenty, downtuned stuff where the guitarists have more than 6 strings and bassists play through Darkglass preamps or Kempers. That’s the sort of stuff that benefits most from longer scale instruments and hence fanned frets etc.
I guess how progressive the music is will have an influence on how progressive the instruments are. If the music espouses the sound, look and ethos of the 60s, then it follows that what they hang on a strap onstage will too.