OP will have access to the FL, but in F he would have access to FFD.
Whether something is "worth" it is not is subjective. Depends on what the money means to the specific passenger. If it is what one drops at a bar after work, it's likely worth it. If it is the difference between losing one's house or not, it's likely not worth it.
In any event, the likely only place to accomplish this is at the airport on the day of travel when AA has control of the ticket.