Originally Posted by
WindFlyer
..... and as a 1P and using miles to UG, you are technically going on the PB waitlist, which will not be cleared until the entire PA list has cleared (and the PA list will have all the GSs, 1Ks and others supporting UGs with SWUs).
"Technically" a 1P may be required to be on the PB list, but I am not sure that is what always happens.
I recently upgraded SYD-LAX, SFO-SYD from a B fare with miles. I was waitlisted for 3 weeks until both cleared at about the 36 hour mark, but I had called CS several times over the weeks to check and was told everytime that I was definitely on the PA list, and that it was a benefit of 1P. There are some other posts that have been on the PA list also.
To the OP, the upgrades are possible, but I would (as already mentioned) choose the flights carefully based on demand!