Not many race cars are four wheel drive? Great off road or on the slippery stuff but unless the Quattro fitted to the A3 measures different wheel speeds between front and rear it is generally front wheel drive...........................
If I had to go out in all weathers I'd pick the four wheel drive, seeing as I don't and as I mentioned having driven both, the 2wd on the road was a quicker car even round corners. I've had many Quattro cars, S versions too, so it's not as if I haven't tried both. I would prefer something with the power output of the S3 with Quattro.
There's absolutely no doubt that Quattro has benefits but for the gentleman in question he may not benefit greatly particularly if cost is an issue, but it's his choice not mine, so my recommendation to him is try both and make his own mind up.