So from reading this thread I learnt that any co-branded card (starwood, delta) won't work because it's "not a real Amex". Citi definitely doesn't. Minus charge cards, so what are we left with? Blue? Can't possibly work with that since it's no annual fee, so it would be unprofitable. I guess it only works with the blue cash PREFERRED. I'm just wondering if it's only that card, why didn't Amex just say so??