Any vehicle with traditional 4WD will want to go in a straight line when 4WD is engaged - there is no differential between front and rear axles. They are locked together and at least one wheel on both axles will turn at the same speed. It won't matter how good the tires are - in deep snow, with 4WD engaged, a traditional 4WD vehicle is not going to turn well.
These Kugas/Escapes have all-wheel drive (Ford calls it Intelligent 4WD over here) - they dont exactly have a differential between the front and the rear, but the clutch pack system should just be called a differential for lack of a better term. The system works very well, and you can turn with ease even in deep snow.
The tires themselves look like they would hate snow - no cross-siping at all, just three grooves al the way around. I'm really surprised at how well they perform. I'll try to get a picture of one on here to see if they are the same pattern as yours.