Having completed a few JAL SAKITOKU advance purchase fares now, I can confirm that the earning rate to QF is cough. Booking/paying for an upgrade to "Class J" earns at discount economy rates (that is, 10 status credits per flight), while an upgrade to F earns at flexible economy rate (that is, 20 status credits per flight). And no minimum points guarantee.
OK, so in Class J you get a wider seat (2-3 instead of 3-3) + tea, coffee or juice; in F you get an even wider seat + a light meal and alcohol. At 1,000 Yen for the upgrade, class J may be OK; at 8,000 Yen, F isn't.
We had an interesting experience at check-in for this flight. The check-in chick was concerned that our bags were overweight and said that the limit was 20kg per bag. I pointed out that we were in "Class J" to which she replied: "Almost Business" :shock: She then allowed us the extra couple of kg's.
Dare I say it; if I book a domestic flight in Japan again I would probably go with Jetstar Japan if they flew the route. Or maybe I'll try ANA if the price is right.