Maybe some former HK pilots can comment. But from what I understand, 60-65K per year per pilot in housing costs over there, education expenses for kids, most trip started with deadheads to Guangzhou or other Asia cities (rare to actually leave HK on own metal), Biz class tickets back and forth to US for recurrent every 9 months as some examples. I don't think the cost of positioning and slight inefficiency in rest requirements delaying ability to operate is that much different from the costs of maintaining an overseas base in HK. Both options have pros and cons and probably similar costs overall.