Here's what banjo player Peter McKee has to say on the subject-

"I learned that when Pete's father took him at age 17 to Asheville, NC in 1936 to see the 9th Annual Mountain Music and Dance Festival organized by Bascom Lamar Lunsford, this was where Peter first saw the five string banjo played, by Lunsford and Samantha Bumgarner, They were both from the Asheville area and both played in an up-picking style, not in the down-picking, clawhammer style. What I have also just learned from my recent trip to Asheville is that, according to one current author/banjo player from the area, up-picking was the far more common playing style of banjo in the Asheville area back then. Thus, when Pete saw the banjo played for the first time by two masters of the regional up-picking style, it changed his life. Pete apparently assumed that what he first saw in Asheville was how the banjo was to be played and he began to adopt this style as the model for what became his basic strum. If you can find the very few recording of Bumgarner on YouTube and you listen closely, I think you will hear the seeds of Pete's basic strum. When I first heard her banjo playing, I was amazed - "That's Pete's strum!" I said to myself."

-from this thread at the Banjo Hangout, his is the 6th post down and he posts as phdm.
I kind of got a handle on Pete's up picking style with the help of Frankham but found I preferred clawhammer with a bit of drop thumb.