Any dedicated snow tire, such as the Cooper Discoverer M/S or the Nokian, will indeed excel in cold climates and in icy conditions - no arguement there. The problem with any of these dedicated snow/winter tires arises when they are asked to operate in temperatures above 40 or 50 degrees. The rubber compounds in these tires are so soft (which is why they excel in subzero temps) that in more mild to warm temps they wear like crazy. The fastest way to kill a snow tire is to keep it on the truck into spring.
If you're going to get a single tire that will keep you pointed straight and happy all year 'round, you have to make some compromises. No single tire does everything perfectly. Dedicated snow tires are best in the cold but stink in warmer conditions due to increased wear and lost handling. Strict A/T tires are pretty decent in most categories overall, but my biggest personal gripe with A/T tires is that they fall real short in mud and deep snow. A/T tires, designed for moderate traction advantages over an highway tire but with longevity in mind, don't have wide enough channels to properly clean themselves of packed snow and especially mud. Compared to the Cooper S/T which is basically a mud tire with more edges and siping added, normal A/T tires (cooper discoverer A/T, BFG All Terrain, etc. ) clog up in mud and are as worthless as racing slicks. I have first hand experience with this, and it made me regret buying those A/T tires. Since I've been putting these S/T (stands for Sure Trac) on everything, I've been solidly happy with these tires. The S/T-C differs from the S/T with narrower shoulder and tread face widths, higher load capacities, and a harder compound to resist cuts and chips that aggressive tires can commonly encounter in severe service, expecially in rocky conditions. That being said, I've only ever bought the S/T tires, and I've never seen these cutting and chipping problems on the tread face. This harder compound, I would venture to guess, would also prolong tread like in situations where heavy loads and more highway driving are encountered. I suspect that the harder compound may rear its ugly head in subzero conditions, and glare ice traction will most likely suffer. Depending on what you want these tires to do for you will likely determine which model (S/T or S/T-C) you will desire. I'm going to try the S/T-C ones out next time. My S/T tires, in 315 size, see all kinds of work. I do moderate off road stuff for work, dealing mostly with sticky clay material, and these tires clear well in spite of the sticky nature of the mud. I like that. They see mostly highway service, and probably about 1000 miles a month of heavy loads (4 horse gooseneck, 36 feet overall or a bed full of material and tools and soil-filled 55-gallon drums). They are wearing very well. Even the guy at the tire shop was amazed at the longevity I'm getting out of these. Rotate every 6,000 miles, check tire pressure often, and you can get your money's worth. Even driving empty during commutes, I am not at all light on the throttle. These tires see hard corners and more than a few burnouts on tar. I'd buy them again in a heartbeat. I wanted a tough tire that would have enough edges to have a prayer in snow and ice in Northern Minnesota and Wisconsin, have enough voids to clear mud well, and be tough enough to put up with me and a 7,000+ pound turbo diesel. I put these tires on everything, and I don't regret the money spent whatsoever. I feel the Cooper S/T tires don't make compromises that other OEM tire manufacturers make on their tires. Cooper sipes the tread the full depth of the tread, whereas Michelin spies only half way down. Wear out a Michelin half way and you'll find that edges and siping start to disappear due to intentional lack-of-depth, and you're left with racing slicks that can leave you stranded or worse.
This Australian Cooper site has better info on these tires than the US site.
http://www.coopertires.com.au/tyres/st.htm
Attention: TDR Forum Junkies 
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Big wide Toyo’s that’s all. :-laf
