I had one of these a couple of months ago, and I've used it on one of my long haul flights recently. As far as the upgrade priority goes, I've been told that mileage upgrades are at the bottom of the list. I presented mine at the F podium in HKG about 1.5 hrs prior to departure and my new BP was already waiting for me as I entered the Wing. The flight ended up full in F and J but remained very empty in Y.