I have been offered free first class seats on the same route i have been downgraded from F to J on. Once on a DXB-DEL, offered free DXB-DEL return.
Second time, on a ticket LHR-DXB-BOM, was downgraded to J on the DXB-BOM sector and offered a further DXB-BOM return. When i pointed out that i would have to then pay for a LHR-DXB in order to use the ticket, which is the same fare as LHR-DXB-BOM, I was goiven a free LHR-DXB-BOM return in F.
Both times were caused where there had ben a change of aircraft.
I did ask for the equiv miles (DXB-BOM-DXB) in F but weas denied them - crazy in the case where i was offered the LHR-DXB-BOM - but i guess they are put on the spot at the time.