Interesting and informative article about the 787 and how they are performing in actual airline service, three years after delivery. Generally airlines seem to be happy with them, apart from the early glitches. Depending what measures you use and what planes are being replaced airlines are getting up to 27% savings on fuel, however up to 20% cost saving seems to be about the average on a per passenger basis.
The article is about the 787-8 and from what I hear the results from the 787-9 are slightly better. The reliability issues seem to be mostly fixed so Air New Zealand should be happy with the 787-9.
AirNZ have 10 787s on order and 10 options. I'm picking that they will take up all those options to replace the 777-200 aircraft by 2020 - there was some AirNZ advice a while back that the 777-200 were still good until about 2020.
http://www.flightglobal.com/news/art...orming-405814/