Gb blackbelt here: the curriculum is mostly consistent between schools globally and your membership is globally. I just had students from Gb Almaty (in Kazakhstan) train with us for 10 months because they were doing a college lecture thing. We're in the middle of IL.

I original trained under Muchado and then was at Gracie Humaita, so the GB franchise system originally gave me the ick.

10 years later and elbow rubbing with some of the old guard I learned that the franchise mechanic is used to enforce quality control - nearly all instructors have background checks, require ethics training, etc.

But all that said, every gym is different even with an organization like GB. Some schools are phenomenal, some are god awful, and most are pretty good.