[Exotic Hadron]

Unfortunately, my friend, I know little about winter tyres. I used to drive on summer tyres this winter. That was challenging but it kinda worked.
What I know for sure is that sDrive does not do differential locking. Bummers. That means a single icy pot, one of the driving wheels in air with little or now contact with snow, and you won't be able to get out. With 4x4 you'll most likely be able to get out of trouble by help of font wheels.
If you can afford price margin, don't even think about sDrive, choose xDrive, that's a killer. I'd better save on winter tyres and opt for all wheel drive.