I ran Sessantas all last winter and didn't get stuck once.
I was able to get up a hill on my way to work when a lady in her Q7 got stuck and was spinning all of her wheels.
I ran Winters the year before and I didn't ever once "need them".
I'm not saying Summer tyres are better than winters I'm just saying first hand experience, you can get buy with some summer tyres over winter.
Yes Winters are safer but unless it's snowy there is not much difference - eg in the dry or wet... only really icey/snowy under about 4 degrees road temperature
This year I'm running winter wheels with Vredestein Sessantas again..probably. not 100% made up mind yet.