Another data point: Refund for four PE BOS-LHR-PSA tickets posted to my credit card today. Made original request with CSR on May 4 because BA cancelled LHR-PSA. May 13 AA emailed me "We're sorry your travel plans changed but your trip is non-refundable." Reached out to AA on Twitter, in a couple of hours they responded that refund was now approved and my request should post in 7-10 days. May 21, status of refund was changed to approved and refund came through today.
AA CSR and Twitter team excellent. Thanks to all contributions to this thread and Wiki!