Pros: Slippery heel for easy off and on of boots
Cons: seam over ankle bone
I always look for these socks as I often have trouble getting my foot to go 'around the corner' down into my ski boots, as I have a snugly fitted boot. They seem to have silicon or some other slippery fabric knitted into the foot/heel so it makes it very easy, even on a cold day with very stiff boots, to get into them. This slipperiness does not affect the boot once it is on: that is, I notice no movement of the foot in the boot other than that which I have created myself.
They are very thin, so allow for a nice snug race-fit of boots. Also, as they are not thick, there is no bunching anywhere, so circulation is good, and it keeps my feet warm. Thick socks = cold feet for me. Thin socks = warm feet, as better circulation.
One small issue, is when tackling challenging terrain all day, and boots cranked down to allow best skiing, at the end of the day, I have seam marks right over my ankle bone, but to be honest, there is no pain there, just an exaggerated seam marking on my foot.
A really good purchase if you have stiff boots for performance but sometimes have trouble getting your feet in your boots.