I have a Gore Pac-Lite jacket that I adore. I want one of those Passion Jackets, but as it is just a want and not a need (and you can't find Gore stuff in NZ that I know of), I'm saving my $$$. Zip off arms are great. 
Anyway, my Gore jacket is a size small and I would say it is equivalent to an NZ size 10. Quite a fitting 10, but the jacket I have is designed to be quite fitting through the torso. In my experience, Aussie sizing is just a little more generous than Kiwi sizing, so maybe the small in this jacket would fit like a size 9 (which doesn't generally exist, I know) in Aussie.
Drink coffee and do stupid things faster with more energy.