I cannot recall the last time (or indeed any time) that I had an op-up on QF. But they have happened on CX - specifically J to F - and very welcome too especially when F on CX was about the best in the air. Also had op-ups on FJ and SK, but these were about 25 years ago. In all seriousness, I'd forget about op-ups unless you can get top QF status (ie CL) and that's 2 levels above QF WP and 3 levels above QF SG (which is slightly above CX MPG in the pecking order).