I think comparing it to metal is just a quick shorthand to say "it's heavy music." > dissonance, instrumental virtuosity, and overdriven amps I'm probably jus

I think comparing it to metal is just a quick shorthand to say "it's heavy music." > dissonance, instrumental virtuosity, and overdriven amps I'm probably just splitting hairs here, but although those elements are common, metal is a really diverse genre (I think the only one more diverse is jazz). Really the only two things music needs to fall under the "metal" umbrella are 1) being heavy and 2) having double bass drum. Sacred Harp seems to meet the former.