Not sure what you mean by "potentially harder". I've met many people who immigrated to NZ because they couldn't get into Australia. They then moved to Australia within a month or two of qualifying for and getting NZ citizenship. It used to take 3 yrs of NZ residency (tho with very lenient allowances for time out of the country every calendar year) to become a citizen but was changed to 5 yrs around 10 yrs ago, so maybe the situation's changed a little since then.
But I don't understand why you'd want to leave, having lived in the US, UK, Australia, South Africa and NZ, the choice of NZ for ease of doing business and life is easy.
In the 1990's it was easier to immigrate to NZ than Australia under the different points systems of the two countries. Virtually immigrant I spoke to in NZ got in because of qualification and work experience in China.