Having used this several times, I would echo 100% what has been said above about making changes to these tickets: if you think there is any chance you will have to change your flight before departure, think long and hard about what your time is worth and whether it balances out the savings. I have had to make a few changes to these tickets, and I have NEVER experienced anything like the slowness and frustration of dealing with the agents at Amex Travel online (whether that is Expedia or whatever). On each call, I was prepared with the exact flight to which I wanted to change -- which has always been the identical route, identical fare amount, identical class of service, and in one case the same flight # just a different day -- and never got off the phone in less than 30-40 minutes. And was left feeling totally exasperated at how complicated it was to switch something that should be able to be accomplished online in 30 seconds.
First there are 2-3 minutes of security verification questions, even though you already had to verify through the automated phone system before being connected to an agent. Then it takes them several minutes to find your reservation, and even though you have told them you want to change the ticket, they insist on verifying every detail of the existing reservation. Then they put you on a 5 minute hold while they review the fare rules to see if changes are allowed -- even though these are tickets purchased post-quarantine on AA, which by definition allow changes. Then you tell them the exact flight number and date you want to switch to, and it inexplicably takes them another 5 minutes to find that flight. They keep saying "I am filtering my search to try to locate that flight". It's unreal. Then they ask if this is the flight you want to change to, you say yes, and they tell you you will be responsible for any difference in fare. You respond, I have looked at this online and there does not appear to be a difference in fare. And the agent will then say "oh, I have not priced it yet. Let me place you a brief 5-7 minute hold while I price this new flight." Finally they come back and say it appears to be an even exchange, would you like to make this change? You confirm, which is followed by a few minutes of fully verifying every detail of the new flight. You think you are done, but no! They then ask to place you on a brief 5 minute hold while they complete the ticketing process. There might be some finishing touches at the end, but I was so spent at that point I couldn't really focus. And then you are told they cannot send you a new email from Amex but they will generate a "share my itinerary" email from aa.com or tripcase.com, which has no fare details. So I am not sure how one has "proof" that it was an even exchange, other than that they never charged your card. And of course the new flight does not appear on the Amex website under "my trips", but another call later to them later in the week (if you have the energy) reveals that their website has been an ongoing problem and many ticketed flights are no longer showing up.
The agents are perfectly nice people, but the systems and procedures they have been given are mind-numbing. And I cannot really see how this helps their overall business, because the extra staffing necessitated by every call with an agent having to take so long seems wildly inefficient. In any event, I am intrigued to read here that AA might take over these tickets -- I'd gladly pay a fee, even though I am ExPlat -- just to avoid this in the future.
Sorry for the long post, this was therapeutic for me to write this down.