Sandman, you're correct, Lunsford did have a unique semi-local way of playing that was similar to clawhammer but included aspects of two-finger (no thumb) banjo picking, but could switch between two styles of playing. You can read a good discussion on his playing style at Banjo Hangout. Basically it was popular in Western NC, but also Eastern Tennessee and Northern Georgia.

And you're also right that he was a big part of preserving the song. His recording of the song in 1928 on Brunswick was the first recording and as part of his folklore research, and he certainly is the basis of a lot of modern research about the song.