I've gotten a number of upgrades, both points and operational, but most (all but one) have been on QF flights with QFFF. (in fact, my first ever flight in J was an op up SYD-LAX, points upgrade to PE, op up to J)

That one upgrade off QF was on CX.
Was booked CBR-SYD-NRT. Weather problems in SYD were leading to rolling delays and I noticed while waiting for the CBR-SYD flight that the continued delays would lead to missing the connection.
After alerting QF found staff to the problem, they finally redirected me onto CX via MEL and HKG. I lost the op up I had gotten on QF21 and was given boarding passes for the CX flights in PE (the original booking class for the QF NRT round trip).
As soon as I got to the CX MEL lounge, they reprinted the boarding passes on CX stock and gave me an upgrade to J.