I hope you don't mind me piggy backing on this thread.
I'm looking to UG my upcoming MEL-DOH flight (with miles). Because it's relatively close to the holidays, there is no U availability, but seemingly plenty of J inventory. Looking at the same flight today and tomorrow, there is no U inventory either - so QR is not in the habit of opening this up for awards/upgrades even very close to the flight.
All of these are J9 C9 D9 I9, so there are available seats. Can I reasonably hope to UG (using miles) at the airport? Any advice?