I think there's a huge difference between buying grey market from B&H and buying grey market from "Joe's discount camera". B&H buys in huge volume from sources they know and they stand behind the things they sell. I would not buy grey from anyone I didn't trust or who only did low volume business (where film could sit on the shelves for years).(posted 8170 days ago)Note that buying "USA" film is no guarantee of quality either. Over the years I've had a few defective rolls of film (all color) and they were not "grey" market.
I'd always advise buying in bulk and testing before any important shoot. Usually stores like B&H will ship all film from the same batch, whether selling "grey" or "USA" film. If one roll is good there's a very high probability they are all good.