For the really cold stuff 4°f and below I break out the NEOS Explorer Overshoes. They will handle anything that my area has to offer. I found out about them from folks who ride the Iditarod Trail Invitational. If its good enough for them, then its good enough for me. I've only had them for a few years, and the coldest I wore them was -6°f. My feet were just as toasty as they were when I started out 45 mins earlier.
