Tempting!
But I decided to stay with my S5 because I have better brakes (Brembo), and better looking brakes, and it would be a hassle to switch them over to the new RS5. There's not *that* much difference between my car and the RS5, except the extra few horsepower, the pushbutton start, and a handful of other minor differences that I can live without. And, the blue is a bit bright for my preferences right now.
It's really just another shiny object, a toy, a distraction...
Consider the wise words of Henry David Thoreau: A man is rich in proportion to the number of things he can afford to let alone.