I have tried YYZ-HKG and HKG-YYZ about 7-8 times in 2008 and only didnt get it twice, mind you I was SE at that time, personally I think the HKG-YYZ is a harder upgrade. Try to hit the 4 day window but mostly just get try to check in on time, on the YYZ-HKG segments I have seen many Elites being upgraded. I think it just depends on what day you fly out.