I have had the opportunity to test the Toyo, Blizzak and Hakkapeliitta tires installed on the same model year Cayenne one day in a empty car park. All tire performed within inches of each other for stopping distances on icy surface which one would encounter at intersections, Blizzak/Toyo tying for 1st/2nd places and Nokian in third.
Having owned the above three makes plus other dedicated winter tires over the years I can honestly say the Toyos are the best overall tire to choose from... I'm now on my third set and my recommendations to friends/family to try the Observe series over the Bliazzak has not generated one complaint.
The only complaint I personally would have about the Toyo is tread squirm but so far I'm the only person who has noticed it compared to the other makes and it's only noticeable on heavy vehicle such as the Cayenne, never found it a problem on cars. The tread life is much better on the Toyo- best of all the tires I've owned over the years.
DRY/WET traction is average with this tire which is to be expected... it's a winter tire for extreme winter conditions and really shows its technology at very cold temps on ice.
If you follow the manufactures suggested air pressure and rotation intervals these tires will last many seasons. The Toyo Observe GSi-5 is the best overall studless tire on the market I found to date.