I too have had good success over the past 5 or so years with Silver, Gold and Elite RU's as well as Elite APD upgrades and a couple of OneUp's. Every upgrade I've lodged has cleared and that would probably total around 15 individual flights.

I have however chosen not to upgrade some flights when I've booked PE to/from the US and have been seated next to people on a couple of occasions (I'd actually say both were around school holiday time) who have had upgrades not clear.

Getting upgrades clear right through to LHR can be a challenge, but for my flight to Europe this year it was $3200 o/w for PE and $4000 for BP so it was actually a no brainer to buy a BP fare. Coming back I had upgrades to PE clear immediately to A class.