My experience is that New Zealand Customs are very accommodating and friendly toward travelling photographers but can potentially single people out randomly for special attention. My last visit to NZ in 2009 passing through Christchurch had a battery of Customs officers surrounding me as I struggled and fumbled with many more pieces of conspicuous camera gear than I usually carry ("you took all that as carry-on!?", the Officer glowered incredulously). I was herded to an open area with an inspection bench and queried where I got the equipment from: e.g. if I had stolen the (you're kidding, I'm not that brilliant at pulling off a swifty!), if I was a professional and who employed me and then what I had been doing in New Zealand (travelling and spending money on diesel!). It was just an extended inspection routine and nothing was damaged or roughly handled. Film was inspected carefully (unopened Velvia 50 and 100F in ProPacks) and several exposed rolls were opened, again for closer inspection. None of the film went through X-Ray as on approaching the X-Ray station I raised the boxes above my head to attract attention to the Officer, explaining I wanted it eyeballed "without risk of damage"). That didn't work on arrival in Melbourne! Mailing film back home internationally is slow and risky but probably no real feasible alternative.