Quite a different scenario. Under the NZ Regs, the AT1 can only be touched if the bank has been effectively shuttered by the regulators. Quite unlikely in the case of our Big 4 banks which are much better regulated now, and i assume would benefit from unlimited liquidity support from the RBNZ in case of stress, as they have done in the not so distant past.
Bank sub debt and preferred stock are great investments in NZ. A lot of the positive economics of banks have been shifted from equity holders to bond holders with the current capital requirements and implied lower leverage.