For the most part, other than looks of course, the front brakes will be doing 80% of the stopping anyway. I doubt you'll gain very much from doing the brakes, and at what costs? It requires more parts and more work to make it fit and for the improvement in stopping power you can't justify it, IMO. The rears control the nose squat that you see on most other cars, for example Camrys (those SUCK at braking!). They are more like additional support for the front brakes than anything else. I think on the newer VW/Audi cars there is more rear bias when using the brakes lightly; that helps to keep the car from squatting all the time and keeps the front brakes cooler and less prone to fade for when you really need them (think emergency stop from freeway speeds as opposed to 20 mph stop-n-go).

As far as looks, that's always a personal preference. I've put about 100 miles on the new brakes and they're continuing to improve as they're bedding in. I'm so happy I got them done, would never go back now.

Edit: BTW, I like the Nurburgring logo in your sig; would love to take my (or ANY Audi) on that track for a few laps.

Also, that third pic that shows my car from the front-driver's side, you can see the OEM front brakes a little. I used to have about 1.5 inches of space between caliper and inside of wheel. Now it's only 3/4 of an inch.