While some have been arguing that the RNZAF should get back into the ACF, that is not what a few of us have been suggesting. Not so much that we do not think the RNZAF should have an ACF, rather we acknowledge that due to funding and political restrictions, it will not be happening any time soon, or without a major change in outlook.
What might, emphasis MIGHT be possible, would be for a short squadron (~6-8) of T/A-50 Golden Eagles which are the training & attack version be brought into service. The initial purchase price would likely be in the range of US$180 - 240 mil. or roughly one-third to one-half the price spent on Project Protector. Not include operations costs like fuel, or personnel pay, I suspect such a programme would have a total cost of ~US$600 - 800 mil, over a 30 year service life.
The would open additional avenues of training which are no longer available to NZ. For one, pilots would have a small number of fast jets which they can use to train on, and open up more opportunities for Kiwi pilots to serve in allied services are part of exchange programmes. Secondly, it would allow RNZN crews a chance to resume independent exercises in air defence. Thirdly, it could allow NZDF personnel to resume training in combined arms ops.
As a last advantage, T/A-50's could give the RNZAF an intercept/shootdown. capability.
As for the NZDF using events like RIMPAC as training opportunities, that is what they are there for. However, AFAIK the intent behind holding these multinational exercises was to reinforce and hone different nations' respective abilities to work together. Not as the time to practice a skill which needs to be maintained, but cannot be without outside help.
-Cheers