I visited Dock Boggs once in the late 60s, and he played me his take of Charlie Poole banjo. He used a regular C tuning and a single barred position that he just slid up and down the neck. He played it in the key of F, starting on the 5th fret with the regular barred C, I believe. I don't remember the tune, which at the time I had never heard before (i.e., it wasn't on the first County LP of Poole), but it was a bright 3/4 piece, with lyrics, and the picking was different from Mr Boggs' regular style.

I was much taken with the style but could not have done a 3-finger roll if my life depended on it. I did work out "Don't Let Your Deal Go Down" in a pretty crude 2-finger version, which mostly shared that chord position with the original.