For us, our 'geographical reality', as NR so eloquently put it, includes deep canyons, wide valleys, lots of bush, and lots of native grass. We have an ideal situation for winter grazing. And no, we are not afraid to do it.
One big thing I would like to mention, is that when you calve in sync with nature, winter grazing stands a much better chance of working. You can't winter graze when you're cows are heavy in calf and needing more energy and protein. We calve from mid-May to mid-July, so in the coldest part of our winters, our cows only need 8-10% protein to maintain themselves. They get 2-3 weeks of stockpiled grass, then 2 weeks of green grass, before they calve.