The confusion is probably due to the different concepts of the cars. AND braking and accelerating are two different physical states of a vehicle.
First of all a rear / mid engine car will react differently to wider tires on the rear than a front engine car does. Simply because of the completely different weight distribution. Depending on what the actual surface is like during braking, the larger contact patch of a wider tire may actually offer an advantage during braking, even on snow. But my guess would be that the difference is predominantly caused because the Lambo and the Porsche are most likely to have ABS systems that are simply faster and thus more effective than that of the Audi. Something else that also makes a big difference when braking on snow: does the ABS allow the wheels to lock up or not. Braking on snow, a locked wheel will be more effective than a rolling wheel, because it basically plows the snow and the snow creates a wedge in front of the locked tire which is more effective than just braking the rolling wheel.
* If you take tire tests as a basis for your decission, then chose a test where the car that the tires are tested on has the same basic setup as your own. Rwd, engine mounted in the front. A tire that works on a fwd car doesn't necessarily work on a rwd car.
To actually know what setup is most effective, you would have to study the weather you are driving in and mount the tires accordingly. If there is little snow, then a wider tire will probably provide the biggest advantage. As soon as you have a lot of snow, then the narrower tire is most effective. But one doesn't do that. You look for a tire that offers the best compromise for the type of roads / weather conditions you will probably encounter. Since I have to drive on roads with deep snow, I chose "as narrow as possible". Even if "wider" might give me a braking advantage, if I can't get the car out of the driveway I don't care how good it brakes.
If you run on roads that rarely have deep snow, then a wider winter tire might make more sense for you.
Last winter I had (Pirelli) Sottozero on the M3, yes. I no longer have the car, I traded it in for the 1M.