Just thoght I'd add to this thread. This past week I had LIM-CUZ and CUZ-LIM on AV. When l left Lima I had totally forgotten about this and also used online check-in so never interacted with any staff until boarding.

Coming back to Lima however, for some reason this thread popped into mind, I had already used online checkin, so was at the gate, but asked the gate staff and they gave me the upgrade. Was certainly pleased since Economy was packed near 100% and Business had 2 people. The service is nothing special on Peru domestic, soft drinks only, no food but Cusco flights are packed full so was great to be up front in a nearly empty cabin and space to stretch out.