They're a great example of what happens when you have good musicians do "RenFaire/SCA" music - which is a category tangential to but not the same as Folk or Trad. or Historical. They have managed to get good commercial promotion, unlike many who do similar stuff as more of a hobbyist level. I certainly don't begrudge their success (envy, perhaps, but not begrudge) and enjoy listening to their stuff. But I would be very careful before citing them as an accurate historical source.