Global Mortgages

I have heard a bit recently about people who have global mortgages set up in Singapore or Hong Kong for property outside of these countries.

Currently in NZ the Mortgage interests are around 8-9% while the rates in Sg/HK are closer to 3-4%, so you can see where I’m going with this.

Does anyone have any knowledge/experience of obtaining global mortgages? I understand that Hong Kong is THE place for this. Any comments? What about Taiwan?