For me the math is worse (yes Majuki you don't need to point I have Aus savings and credit card accounts; I'm hypothesising the situation where the AUD is low and I do not wish to utilise those savings).

My wife can draw cash with Unionpay, which is 0.42% over the Visa rate
Add the $2 per $1,000 for 0.62% net cost

Alternatively I can card my HKD cards
Unionpay: 0.42% + 2% surcharge - ~1.3% in miles = 1.12% net cost
Visa: 1.85% FTF + 2% surcharge - ~2.07% in miles = 1.78% net cost

(I'm roughly earning 1.3 miles per $ on Unionpay foreign spending, 2.07 per $ on Visa foreign spending, and I'm using 1cpm for valuation)