I disagree about the worth of going all A400M. Yes, it would give a maximum amount of strategic lift, it would also mean that all the tactical lift was done with strategic airlifters. Something a number of services have known from their use of C-130's is that often the load needed for a given location is much less than the "maximum normal" load, nevermind max possible load for a C-130. Going all A400M would mean even more of the time, the airlifter will be at much less than a full load. Given that the operating costs for such a large aircraft are likely significantly higher than those of short/medium tactical airlifters, going with an all-strategic fleet sounds more expensive than really needed.
Plus I doubt that an A400M can operate from some of the places NZ might need to fly into, either due to aircraft weight or length of runway required. I think NZ needs to at least maintain a two tier fleet of airlifters, if not actually returning to a three tier fleet.
It is worth noting that the RNZAF airlift capability of today is less, in some areas significantly less, in all areas except VIP and strategic troop/personnel lift when compared to the period between 1976 to 1998, and that there was a significant loss in strategic cargo lift after 2003.
The B727-100QC could only lift 8 vs. the 11 pallets of the B757-200, but the B727 could lift ~17,000 kg each vs. only ~10,000 kg each for the B757, and there were 3 B727's instead of the 2 B757's.