No one knows exactly how many people the Kiwi diaspora has taken from these shores, but it's a lot. Some commentators contend New Zealand is really a nation of more than five million people, only four million of whom live here.
But it's not all one-way traffic. Some Aussies call New Zealand home. In fact, they feel more at home here. Think of some of the league imports like retired Warrior Steve Price, whose public comments suggest that Auckland reminds him of the Sydney he grew up in.
The business migrants to New Zealand are a different category. There's a suspicion that many are just slumming it until something bigger and better comes along.
Which is something of a mystery, since if there's one area where New Zealand is streets ahead of the Aussies, it's the ease of doing business in this country. The tax system is flatter and simpler: there are no stamp duties, state or payroll taxes. Such is the ease of setting up a company that concerns have been aired about Godzone becoming a staging post for transnational organised crime.
Then there are the unions, which in Australia are of the old-school variety. Just ask the chief executives of Air New Zealand and Qantas who has the easier task.
But it's not just the headline issues that make doing business in New Zealand better than Australia, reckons Edwina Paddis, who migrated from Sydney with her husband and children two years ago.
New Zealand has a better business culture, particularly for small business, she contends. There is more support for the producers and growers, she says. New Zealand's food and dry goods retail sector might face a supermarket duopoly but it has more choice, she says, citing the independent Nosh and Farro chains of stores.
"Back in Australia, [the equivalent stores] are owned by the two main players [Woolworths and Coles]."
There is a difference in the business culture too.
"In Sydney it's tougher, it's really competitive and people don't have time, people are more guarded," Paddis says.
"The biggest thing that has surprised me is that people actually give their time and listen. My kids [11, 9 and 7] came here and said 'Mum, everyone smiles'. That's the first thing they noticed."
Paddis says the community spirit of a small town still exists in Auckland and it is this esprit de corps that led to her founding boutique food business Inspired Food.
"All these opportunities for me have come about from just talking to people."
You would struggle to find a more passionate advocate for this country than Paddis, although she concedes that when it comes to the footie, she still backs the green and gold.
Inspired Food is a gourmet food business pitched at busy families who like to entertain with excellent fare.
As Paddis says, "If someone drops in, it's all there."
The sweet range is dominated by the traditional dessert Rocky Road, which comes in four flavours: dark chocolate with hand-roasted walnut, white chocolate with cashews, peppermint or peanut butter.
The savoury range involves cheese boards, handmade parmesan biscuits, oat and seed biscuits, onion jam and pear and apple chutney.
Success was almost instantaneous: "I pitched 13 items to Farro and they took 11."
Besides Farro Fresh, she has distribution through Moore Wilson's in Wellington and a range of delicatessens in Christchurch, and is seeking to expand her reach in the search for greater production scale.
"I definitely want to get the volume. I would love to export back into Australia because I think the New Zealand food brand is exceptional."
Her South Island walnuts, for instance, give her an edge, Paddis believes.
"They have got this fresh, honey flavour to them."
This raises the prospect of the convicts - who have already claimed our pavlova, Phar Lap and Crowded House - putting in a claim on our walnuts. Never mind, Paddis is adamant that hers is one business that is staying on this side of the ditch.