[LastFrontierBimmer]

I had a 2011 A4 Avant before buying the 2012 535xi. (I decided the A4 just wasn't big enough for me and passengers.) Being in Alaska, I always run winter tires. Frankly, the A4 handles better in the snow. As the OP said, "like it's on rails." Quattro sends equal power to front and rear all the time. The F10 xDrive understeers, i.e., plows and wants to drift wide. You've got to kick it in the ass (throttle) and crank the wheel tighter to engage the front drive, then she engages and all is reasonably well. It's rear-drive biased in my estimation and cranking the wheel and staying on the throttle - even increasing it a bit - seems counter-intuitive but it works. I've learned to adjust. They're completely different cars - the A6 would be a better comparison. I like the F10 535xi much better but drivability in snow isn't one of the reasons.

PS: I always run winter-specific performance tires. But then, I much prefer a socket wrench to an adjustable (crescent) wrench when the job calls for it.