So reading between all the other stuff that has been written. Would you really need a 4x4 with diff lock etc to cover the odd bit of snow on our roads or would a awd with winter tyres do just as well. Not counting for height clearence. I just dont really want to buy a x5 or a range rover for the odd couple of days.
Most AWD designs are done for cost, and thus its almost as likely to get stuck as 2wd, due to the way all the diffs work. Some has LSD options which help to an extent.
But as others have suggested, for that 1 day a decade? In 15 years of Omega ownership, I've never had (unprovoked) issues, and in all my years driving, the only winter issues I've had was a transit not wanting to go straight or slow down on an icy decline, a FWD struggling (but made it) to get up a block paved incline, and roads that you would never attempt as the snow is significantly above the lower front bumper.