Well, we drove through some slick snow/ice about 3 weeks ago on the original Michelin Energy MXV4 tires. Granted, they were old and pretty well worn, but they sucked. I ordered new Yokohama Geolandar HTS G052s and had them shipped to home - I had them installed at a Porsche dealer I used to work for ($60 for mounting/balancing and a perfect alignment - sweet!!)
So we had this nasty storm roll though the Washington DC metro area last night (well most everything was affected be the same storm east of the Rockies I think). We got snow, wet snow, ice pellets, sleet and freezing rain all intermixed. Needless to say the roads are a complete mess and the temperature is not high enough for the chemicals to do their job effectively (with temps expected to drop to the teens tonight).
I normally drive my '97 540i/6 everyday, but with about 4 inches of ground clearance, an open rear diff and summer tires, my car doesn't even like an inch of snow, much less the crap that fell last night.
So I took my wife's X5 3.0i Sport to work - and what a non event it turned out to be with the X. I didn't shovel the driveway - I just backed out over the 3 inch lip of ice that had formed against the garage door and just drove through the snow/ice that was piled up against our driveway from the street plow. Going through the street was no problem despite the sheet of ice that had formed under the compression of snow/ice from being driven over prior to being plowed. The tires provided excellent traction and didn't even invoke the ABS under light braking. I found some unplowed streets and drove through them without issue - the DSC light didn't even flash until I hit the gas pretty hard. The main roads were basically slushy and lane changes were made very carefully due to the snow-based lane dividers - still no issues - just a little tugging from the steering wheel. There was no time when I felt that the X was ever out of control - it did exactly what I wanted it to do. This was certainly not the case with the old Michelins.
When I got to work, donuts were in order for the open and unplowed parking lots. Those were done quite well with the DSC off - the X5 drifts quite well I must say :-)
So in regards to new G052s in very nasty snow/ice - they performed very, very well. They're also very quiet and smooth on dry pavement with no bouncing as I had heard other people report with sport suspension.