An FYI for WiFi YYZ to HKG and vice versa. When you are going the polar route you will not have Wifi for approx 8 hours. My experience is you will have WiFi first 4 Hours and last 4 hours of the flight IF it is the polar route.
On my last flight a person was giving the flight attendant grief about how he paid but there is no WiFi signal. I had to intervene. I also pointed it out to him it clearly states this point on the WiFi card.
Depending if you are paying out of pocket or not it may be only worth it to pay for WiFi on the last half of the flight.