Shearling lined boots
 

does anyone have any experience with shearling lined boots? I ride down to 10 degrees F. I tried them on and read an info card saying they work best with bare feet! It recommended wearing just a thin sock if necessary. I've always worn the thickest wool sock I could find-plus a chemical warmer for below 25 degrees. So how warm is shearling? What thickness/material of sock is best for maximum warmth? I haven't bought the boots yet. They are on sale For $70.