Any expat post you are not going to save anything in the first year at least. Especially if you have wife and kids in tow. By the time you've bought cars, furnished places, etc etc what ever tax free dollars you have will be eaten up.
Housing in Dubai is becoming an issue across the board. You either end up in a high density apartment building or miles out of town. The landlords hike up the prices in the prime areas out of reach of airline staff allowances.
At the end of the day it is a quality of life thing. Nice weather, safe family surroundings, good lifestyle (at a price! but at least you have the disposable income to have the choice) compared to freezing your nuts off on the ramp in LTN/YYZ/ABZ or wherever and having to put in 70 hrs a week just to pay the tax man half of it.
I've been an expat 20 years in various parts of the globe and in some instances could have earned more staying put in UK, but feel I would have missed out on a whole lot more.