Are you going to be revolving the balance? If yes, then I would keep the balance as low as possible and not use the card and pay the extra fee. However, if you are going to get your loan money in or be able to pay the balance off quickly, then I saw go for it. Another issue, do you have a trip in mind that this gives you the needed balance to redeem?

To the OP's point, AA could devalue the mileage currency. They generally do notify with sufficient time, but still a concern if you are saving up miles over a long period of time.