As I mentioned in the updated first post, National has taken some steps in the past year to better police their codes (I've often wondered if it's better for them NOT to be overzealous in controlling the codes: I'm sure these codes generate substantial and presumably profitable business that they otherwise would lose). You are certainly more likely to be hassled at a counter than as an Emerald Club member. You are also more likely to be hassled at a small location. You have to decide whether it's worth the risk. If the savings are substantial, I'd go for it and have a back up plan.