I recently replaced my US Sport springs with Euro S-Line springs (obtained in VWvortex groupbuy) into my A3. I kept my US Sport shocks, and the Neuspeed rear stabilizer bar (set on soft both before and after the new springs were installed).
The handling is slightly firmer and noticeably more neutral. The A3 is less floaty after going over highway undulations. I can also get the rear to rotate more, especially when braking.
Thanks for the follow up on the question hesaputz.
a3_yuppie that is good to hear. I have a 07 premium and I did not like the way the car "floats" at higway speed. I think I will be happy with the decision. Call me crazy but I am not a soft ride kind of person.