If you're doing a novated lease, sacrificing the payments out of the segment of your income that's in the top tax bracket, and are doing 25000km a year, you're more than marginally better off, I can tell you. I'm about to enter my third 3 year/25000km a year novated lease and it's worked.
It's a lifestyle decision though... and the 7 year rule isn't hard and fast either - a colleague is currently leasing an early R33 GTS-t with no hassles.
I've not had to dispose of cars mid lease mind you, and that could get difficult if your residual is high (50%) and the car is worth less than the payout figure.
If you're not sacrificing out of the top tax bracket and you're not doing at least 20000km a year, then forget it - buy the car "conventionally"