The difference between K2 nylon and K2 mohair blend is huge (I have both)... K2 nylon skins are simply AWFUL if you want a skin that glides.
K2 nylon skins are heavier, thicker and most importantly they simply just don't glide across the snow. If you want to enjoy the skin track up, DO NOT buy K2 nylon skins, they are like having snowshoes on your skis, that's how much they don't glide. They are more durable and will grip better than the mohair skins, so in certain conditions like skinning up steep powder, nylon may work better, but if your doing any long duration skinning they will just help to exhaust you quicker. However, unless K2 has improved the nylon skins, I literally think they should be taken off the market.
K2 mohair blend skins are lighter, thinner, glide way better and overall just have a better feeling across the snow on the uphill. K2 mohair skins may be more expensive than their nylon counterpart, but it's money well spent. Also, Mohair skins may not last as long as Nylon skins. But with that said, if you're going to buy K2 skins, definitely stick with K2 mohair skins, they are lighter, thinner, and glide better! Your legs will thank you when you get to the top.. or while skinning back to your car.
K2 mohair blend skins work so much better, although they may be slightly more expensive (they are totally worth it, when compared to K2 nylon skins).