The cost of living calculator they put up[1] suggested that I'd be losing money as a single income earner for my wife and daughter in Auckland, while I can support them here and bank literally 1000s on top of my living costs and mortgage here.
I don't know exactly what I'd get in Auckland though, I assume it's estimates are middle of the range, so it's not quite a fair comparison but the general picture fits; in general living costs in NZ are a bit lower (excluding Auckland housing, which is more expensive than anywhere in AU except for Sydney) and the median salary is _far_ lower.
Also, preferences may differ, but I grew up in rural NZ and inner Melbourne is a much more interesting place to live as an adult; the country was pretty fun as a kid though.
[1] https://www.newzealandnow.govt.nz/living-in-nz/money-tax/com...