Sorry for intervening in your decision regarding all-weather tires,
but why wouldn't you buy summer tires and a separate set of winter tires.
You got an expensive car and you live in an area with relatively hot summers and cold winters. So all-weather tires would kinda suck during most time of the year. It's not that expensive to buy a set of winter tires (here in Europe, most people who have winter tires mount them on steel -cheap- rims; if you don't have those rims most people think you don't even have winter tires on the car)
just my 2 cents,
good luck with the decision