Originally Posted by
tutkija80
I have experience booking hotels through this method.
You will be charged in full immediately upon booking. The Membership Rewards points will post to your account as normal (billing cycle after statement closes with that booking).
If you are booking through the “flexible cancellation” policy, you will be refunded at the point of cancellation, and them Amex will presumably reconcile the Membership Rewards points that were issued and claw them back.
This has been my experience as well - prepaid doesn't have to mean nonrefundable. It usually is, with OTAs such as Expedia, thus why we get accustomed to that being the norm. It might be a unique rate for Amex, but I don't really know.