The AMEX gift cards are problematic for vendors not just because of higher fees but also, depending on the equipment they're using to run the cards, they sometimes won't go through. I had a card that had over $100 on it at a convention (not D*C) and it kept coming back declined even after I called the compan and they confirmed it had a positive balance. The vendor and the company even told me that some machines just don't work with those cards. Even the restaurant where I work can't run those cards because of our system.