I have noticed how my spacers affected the handling the day I installed them. Spacers increase the scrub radius, and this lessens road feel/responsiveness to an extent. Steering effort is also increased. My steering isn't significantly heavier, but it is noticeable. I also noticed more steering kickback on bad roads. I'm only running 10mm spacers too. But I am more confident in my car. Wider track has been beneficial on the back roads. This thing has amazing road holding capabilities with the spacers.
Current: Alpine White F10 M5|H&R springs|12mm/10mm spacers|Eisenmann Race
Sold:Imola Yellow RS4-KW V3|MTM 10mm spacers|Hotchkis rear sway bar|APR Stage 1|Milltek Catless|RNS-E|Euro RS4 Flat bottom Steering Wheel