I'm still a few years away from retiring. I came across this posting at the Kiwsaver website, that I found interesting.

Is there any downsides to this agreement?

I'm guessing it would be more expensive to retire somewhere like the Tasman than Northlands

http://www.kiwisaver.govt.nz/already/get-money/early/moving/

"From 1 July 2013 you are no longer able to withdraw your KiwiSaver funds early if you have moved to live permanently in Australia.

The Australian and New Zealand governments have worked on an agreement that makes KiwiSaver accounts and compulsory Australian pension savings portable across the Tasman. The portability arrangements allow a person who has retirement savings in both Australia and New Zealand to consolidate their savings in one account in their current country of residence"