There's an elephant in the room here: do you have a legal way of emigrating to the USA? It's not a very easy country for foreigners to get into (or, at least, to work in) nowadays.
Spot on. As much as we'd like to move to the U.S. the biggest barrier is that small matter of a green card! We actually love Australia, and Melbourne is a wonderful city, but we do face certain disadvantages building a startup from here. We're still doing it of course and, interestingly, in our particular niche (tools for domain name investors) Melbourne actually has a few global players (e.g. Trellian, Flippa). Down the track I see us having some kind of U.S. presence. There's always a way...