Yes, I can confirm. Japan MAC prices are about 30% higher than Canada, and Hong Kong prices are about the same as Canada, or slightly less. The last time I was in Hong Kong, I spent a loooooooot of $$ on MAC because it's just too expensive in Japan.
You can also find a lot of hidden gems at Sasa and Bonjour if you ever go to Hong Kong!
I love the Duty Free in TST, they have a lot of traveller's edition things - the last time I was there (this summer), they had an interesting assortment of lip palettes and eyeshadow palettes that I had not seen before. I actually bought a set of two fluidlines that came with a cool leather bag and a mini 209SE brush.