Shaw can win more votes. He can also do something more important: he can put the Greens into power. Picture the look on Peters' face if the Greens blocked him from Government. I would vote Green 2017 just for that.
Sufficiently interested in this scenario I looked up James Shaw's maiden speech. Indeed he is an interesting character with a colourful business background.
A couple of excerpts that must have had some Green MPs cringing:
Now, I’m a huge fan of the market. When it comes to setting prices and allocating scarce resources it usually beats the alternatives hands down....
I am not committed to partisanship for its own sake. Political tribalism is, I believe, the single greatest barrier to creating enduring solutions to the great challenges of our time.