I knew the not a proper quattro comment was coming, I died a little inside when I read it
@veeeight
I know you hate that. Sorry.
I'll give you one quick example of why it's not "proper" quattro or "proper" full time AWD.
When you touch the brake pedal, the Haldex automatically disengages, and you are back to being a front wheel drive car, you lose all drive from the rear wheels, any engine braking is not transmitted through the rear anymore (useful in many situations, eg: descending snowy hills where your gearing isn't low enough). A "proper" AWD centre diff equipped car would not have this issue.
There are also many more examples where Haldex doesn't cut the mustard (the lack of centre diff changes the way the car handles), and in handling terms, AWD vs RWD is an even more complex subject.
This "feeling planted on motorways" thing is debatable with Haldex, as in those situations the Haldex is normally disengaged, and the car is a Front Wheel Drive car (not so with "proper" quattro).
However, as a traction aid (getting off the line), Haldex is a brilliant cost effective solution for the A3.
But you won't defy the laws of physics, so whilst you'll have more traction getting off the line, you won't necessarily have any more grip (around the corners), so leave ESP switched on (or in Sport if you must) in this weather when driving on the public roads.
If you're having trouble getting out of a snowy car park, and the traction control keeps cutting in, then this is one of those rare situations where it would be beneficial to turn ESP fully off to enable forward motion and momentum to unstick you from that local difficulty.