Again, I don't know anyone who wants to come back. Some have scored a green card in the lottery and have moved to the majors. There will be green cards at some stage, could be two years, could be 5.
It's not all about pay, personally, me? Job satisfaction. But if you are after the pay and commit to the States and get to spend a decent amount of time at a major, your 401k v Super in Australia for the similar amount of time will make the Super look piss-anty.
It's all about timing.