All depends how much you HAVE to use the Zed, I'm coming up to my 4th winter with mine, never had winter tyres and always driven through the winter with no problems. If it is heavy snow and I don't have to use the Zed I don't no point risking some other tool sliding into me is there
At the end if the day you can have winter tyres, snow sock even chains on but if some idiot is out of control you will still have no chance of getting out of the way