Second @OrderOfTheKookaburra - come and look at the new Aussie board, and cost of living in particular.
I agree with all the negatives and positives here, but after 15 years in Sydney, I'd say it's hard to appreciate the positives.
We're in the top income bracket, and whilst it could be a lot worse for us, I still shop at aldi. We use mainly private healthcare, but that is exorbitant, and the waiting lists in public hospitals are ridiculous.
The mortgage rates are going up and up, petrol is ridiculous, and there are A LOT of people "doing it tough". The salaries were relatively high 15 years ago, but the cost of living has changed that completely.
Anyway, I'd only suggest coming over if you had family etc to reconnect with. If you're also close to your families, and would be leaving them behind, I just wouldn't.
Having said all of that. You could give it 2 years. Work out the costs of moving, and if after 2 years you think it was a mistake, go back. It takes the pressure off, and means you're much more careful with money.