While dated, I did that flight in 2012, none of my upgrade requests as a WP At the time were successful. On the way home ran into some QantasLink pilots who were in J. QF then were sending pilots to Seattle for flight sim training as it wasn’t available in Australia. Bear in mind there’s paying PAX and rewards tics too so flights with F cabin will also see less J seats available - makes for a tight squeeze
In MARCH 2014: I went to San Fran as Gold although took my Plat card as the new one hadn’t shown up, that’s another story about getting into F lounges (including as a plus 1) and chatted with a number of other PAX who suggested 3-cabin flights gave far greater opportunity for J upgrades (a lot more J seats) than 4-cabin flights and that their success rate of regular upgrades on the 3-cabin was pretty good.
So given the order etc, month of flights you may find upgrades are rare ..... I don’t fsncy your chances given the discount tic....
I found Premium Economy fine at the time and was what I could financially afford (even given it was a conference so negatively geared tax deductible against a professional allowance) (Previously, I did get an at the gate op-up to PE in 2008 for FREE and of course we all know free is best haha )
That said, I do think the extra 3-4 inches of recline makes a significant difference.....and ask nicely you might even score some J class champers, wine or spirits ....