If you do move on a 457 visa, be sure to negotiate LAFHA (living away from home allowance) up front. It's a tax break from the governement that can offer relief on up to 30% of your salary. This costs your employer nothing beyond a bit of paperwork, but a great many refuse to process it once you're in the position, and the potential upside is quite great. Negotiate a salary first is my tip, for otherwise the employer may talk smaller numbers given that your percentage take home under lafha would be significantly higher.