I'm Wellington born, but moved to Aus when i was 5. Im still in Australia 15 years later, having spent nearly my entire schooling life here. I still associate myself completely as a NZ, even though most of my family have either left or passed away in NZ.
I fell its all about how a person associates themselves, I feel as much as a kiwi now as I always have. My cousin on the otherhand, who was in a similar situation, feels more Australian than Kiwi.
If a player associates himself as a kiwi, whether he was born here or not, and he is good enough than that is enough for me for him to be an All White/ Black etc..
I'm in the same boat as you. I came over to Australia when I was 10 and am still here 12 years later and consider myself a full Kiwi. The fact I did most of my primary school there and have many memories along with family there. It would be different if you were only 2-3 years old and can't remember anything and then left the country for another.
If someone wants to represent NZ because they feel Kiwi and want to use it as a way to thank the country for giving them opportunities to be successful and provide a positive environment (especially those from less fortunate backgrounds) for them and their family then I can't complain.
Those who just want to represent New Zealand for their own self gain probably do not deserve the chance in my opinion because that shouldn't be what national team football is about.