RichardMEL, that made interesting reading - thanks! I guess the other thing to consider is the relative value of 100,000 QF miles vs. 100,000 generic US FF miles. Looking at award flight levels, upgrades etc the QF miles are worth significantly less.

I'm in a similar situation to you, in that most of my flying is international in discount Y. Thanks to the cheapest Star RTW and 3 cheap return flights to NZ this year, I'll have Star Gold on AC. I wouldn't even have hit silver on QF (or NZ, for that matter, which is the one *A FFP which has followed the revenue-based model rather than the mileage-based model most Star carriers have used). The thing is, I can't help wondering how long it will be before all airlines figure out that the QF/NZ model makes far more business sense than the UA/AC model.