I don't have much to add to this, since I've never had much use for the concept of "authenticity" in music -- I think music is at its best when people aren't too conscious of the "proper" way of doing things.

But this topic did remind me of an interesting Paul Simon interview I read once. He said with a chuckle that when he recorded Davey Graham's "Angie" (on S & G's "Sounds of Silence" album) he made a mistake. Since this has become a ubiquitous guitar piece, and many more people have learned it by copying Paul Simon than by going back to the source, he now hears his one-time mistake being played note-for-note on a regular basis.