I believe that the Siri Remote functionality can be activated on the latest Apple TV by using an Australian or US iTunes account.  

Have people actually done this with a locally purchased unit?  And if so, are there any limitations in doing so?

I am contemplating purchasing one (as a sky replacement) and wondered if you need to purchase Australian or US hardware for this to be available, or does this work on units purchased in New Zealand as well?  If so then I would assume that there is no difference in hardware but this is difficult to confirm.  

e.g. If there was different hardware versions then Apple could not "turn on" Siri searching at a later date - assuming they ever planned to do that.

Also does the user additionally login using their Apple ID and does the country associated with this ID affect Siri?

Any other relevant observations with this would be greatly appreciated.

Thanks in advance.