no answers yet... Come on!! I want to know, too!
I am not a member but I intend to join. I have what I consider to be a substantial amount of experience dealing with the SCAA Barista Guild and some of its members in the South East United States. I can say with total sincerity that the guys who make up that group are among- no- they are the core, most dedicated baristi I've ever met.
I'd bet the same is true of Roaster's Guild members. The knowledge that BGA members contain and share is invaluable.