I've always bought from him in person. His stuff is legit, perhaps a bit over priced. His constant, "I can sell this online for more" schtick gets old, but he seems like an ok guy.
He does have that arrogant, abrupt, expert collector attitude, so I imagine when he meets another opinionated, arrogant, expert collector the sparks must fly.
I always wind up chatting and enjoy it. I think it helps to know your stuff before you buy vis a vis price, but what things are, is accurately represented in my experience.