From my biased point of view, I think the analysis of Chinese people in Vancouver walking into the Chinese agents to buy a ticket is somewhat true. Partly due to the linguistic problem (for some,... i guess.) or simply because they do not believe buying direct from the airline will be cheap. (at least from my experience)

20% discount on F-class ticket is awesome! But I know a friend, whose family (members of 5) bought full-fare business class tickets YVR-HKG and got all upgraded to First class. (the promotion). That means nearly 1/3 of the cabin was his family members. So, as long as this promotion last, the question is whether you want to fly both trips on First class for extra $$$ (even with 20% off), or you will be satisfied with 1 first class segments, with much lower full-fare business class fare. But of course, this will not be an issue for those who are extremely well off...