But you've also to think of the longer term. You may be a Captain in a US regional but where to from there? Going to spend your adult life in the US? You may find that SO gig in Australia pays just as well, and the wait time to FO isn't that much.
If you look at Airline Pilot Central there are Captains in Delta who have been in the company 4 years, at Alaskan 5 years. So if you are good enough and able to get in there are opportunities there.
But as you say you will want to settle in the USA if you were to go down that path.
In terms of money though you are way better off in any Legacy airline in the USA than any jet airline in Australia especially once you start factoring taxation into the equation. All depends on where you want to live in the longer term.