Totally agree Daylight Robbery - interesting that everyone runs to all sorts of conclusions - when as mentioned by others VA does this, and has been doing it for years, as is JQ.
Quite simply the NZ crews just don't mix and fly with the AU crew. Works at the other end of the terminal...
NZ vs VH tails will be the only difference you will notice - allows better utilisation of the fleet, and cycling the a/c - the current ZK ones would have a lot more hours vs cycles than an VH aircraft.