Is it pay related or working conditions? From what I have heard the pay, despite the relative cost of living, is pretty poor when compared to other providers.
I'm not sure exactly what you mean here. Are you suggesting the relative cost of living is cheap/reasonable? If so then you need to do some more homework as the cost of living is actually extremely high.
Why did I leave? Several reasons the first being it was time to broaden my and my family's horizons but I wouldn't have entertained doing so unless there was a financial reward so certainly the fact that I am able to earn twice my NZ salary overseas (tax free) was also a big incentive.