I'm sure the OP will have spotted this if relevant, but I booked LGW-SJO//TPA-DFW-LHR in a recent sale.
The BA site gave me the option of flying back to the UK on any BA or AA flight, but the AA site was only showing BA flights for the return TATL.
Sadly we have the sloping seats on AA - at least for now. However if I read it correctly, a thread on the AA forum suggested that the refit was now back on track.