Why would you change to a new visa that the rules may change for it and it only lasts 5 years then you will have to go back to a retirement visa or something else if they stop the DTV .And if they up the financial requirements for a retirement visa in a few years but grandfather the older visas your going backwards. But each to their own.
New Zealand is the same I just walked down to the local temple and got the head monk to sing and stamp it and then post it to NZ it's worked every time so far. But same as you has to be posted to them.
Cro Murl You're right about thai immigration way better to work with try work with New Zealand immigration at least with thai immigration you can talk to a real person .