Disney no longer has a relationship with Amex. All of their credit card related discounts and rewards are supposed to come through the Disney Visa exclusively.
We were considering the Amex because of the discounts that had been offered through them. However, we learned of that Disney was entering into an agreement with Bank one for the Disney Visa so we waited 'till it was available and got that one instead.
Don't know how often or how exclusive these offers will be, but I used the Disney Visa discount for our upcoming trip in June and will be getting a Disney Rewards Debit card prior to the trip. This will be enough to pay for about half of our AKL hotel bill. The difference will be charged to our DV to start accumulating more Disney Rewards for the future.
We use this card for everything and use it like an Amex, i.e. we pay the bill in full each month so there is no interest and no card holder's fee, so in the last year we have accumulated more than $500! For us, that is free money!!