I had a case where I booked an international J itinerary. During one of my weekly reviews of my upcoming bookings, I noticed an aircraft change to one without a premium cabin. At that point in time, I managed to snag a pair of MCE seats for free.

Several weeks later, AA called me informing me about the change, and processed a partial refund for that segment, which was surprisingly significant.

After the reticketing, I noticed I would have been charged for selecting a MCE seat. I did not get a group 1 BP for that segment, though still was awarded 2x EQMs