are you sure about cx pilots being low regarding productivity?
they fly about the same as europeans regarding hours, plus they cost less tax/social contribution than their colleagues, and the wages are in hk-dollar(which lost about 35% to the euro in the last years)
also you have to take into account that cx only has wide bodies,which need more experienced pilots in general,so you would have to compare the costs with high seniority guys in european carriers.