Screw the big cities.
edit: I guess lots of people just live where they were born, or move to a bigger place for the education / work opportunities, or the lifestyle. Then there's the sea-changers and tree-changers. I think I've undergone a tree-change.
Adelaide is not a big city. Adelaide is a small, very affordable city. A big city is Sydney, Melbourne, Paris, London, NY, Tokyo.
Its good you have found something you like, but I have no need for so much space. Why would I, I think it is wasteful. And having to own a car, I would hate that.
I'd give a move like that serious thought, especially if you can land something decent in the area. The salary delta will more than be eaten by what you'll pay for rent. The hardest part in our area is finding comparable social stuff, but it's really not that hard... There's tons of like-minded people around.