Hi Adam, welcome to the forum.
It looks like you could go either way with getting into NZ. Applying for a LTBV can be quite tiresome and long-winded with business plans and other stuff flying around, but it can be done. If you wanted to take a simpler route, why not apply as a skilled migrant and, once you have PR, you'd be free to start up your own IT business if you wanted to or use your new degree if you so wished.
Perhaps it would be advantageous to try to find a NZ job within your field which would not only gain you extra points for your application, but would also give you time to explore opportunities and contacts in NZ for when you want to start your own company. Business practices there could be quite different to those you're experiencing now.
Personally, I'd go for the easiest and most assured way of getting in, then, with PR safely under my belt, I'd see how I then felt about my choices and which way I wanted to go. You can submit your PR application with either 120 points or 170 points but, of course, you'd have more chance of being selected quickly with 170. That's not to say you couldn't get picked with only 120 points. If you find a job offer and apply with 170, it would mean that you would need to stay in that job for a minimum of 3 months because you claimed points for it.