For Fans of Flatpicking Guitar Magazine
Hi Phil, seems to be a popular topic on the web. On one forum, it was mentioned it was not quite as thick as a dime. On Acoustic Guitar an article read: He shapes his own tortoiseshell picks from blanks and keeps two on hand at all times in case he drops one: “Guitarists don’t need to embarrass themselves by not having a spare pick in their pocket.”
Others have suggested its not so much the pick he uses, but his technique. He lets very little of the pick extend past his fingers and he hits the strings perpendicular to the the top, rather than "digging in" and pushing the strings down as the pick hits them. You can deliver a lot more power without buzzing if you use that technique.
These tidbits were found across the web doing a Google search, I'm no where near that caliber.
I've been using a Martin .73mm pick and it seems to work for me. :-)
I used a martin .73 pick for about 3years ,and i think they are pretty good too, but i recently bought a bluechip ct55, a lot of money for a pick but worth it...