I don't agree...
The S3 is faster off the mark, with the majority of drivers onboard.
Certainly quicker through 1st.
I'd still bet the 0-60s would be quicker for the majority of S3 vs A3 type shoot-outs.
The A3 can be as quick...but it's harder.
I know my Golf can match a standard S3 up to illegal speeds...but even on a good day, I'd be lucky to get a launch as good as a mediocre S3 launch.
Off roundabouts it's different...LSD + better suspension = faster car.
But off the line...the times, and experience tell you that the 4WD car will edge it in most circumstances.