Matt - I think if you're saying that Anne Briggs, Shirley Collins or Bert Jansch sang in an understated style you're using the word to mean something different from Jack. They didn't yell their heads off - so perhaps the part about the spectrum running all the way to 'overstated' may not apply - but when any one of them sang a song it stayed sung. Bert Jansch's was the first folk voice I fell in love with, & part of what I loved about it was how big & rich it seemed.