My winter feet solution is a little involved but very effective. After getting weary of cold feet and on one occasion getting frostbite thanks to my neoprene overbooties, snow packing in through the SPD hole, forcing it's way all around the toes, then re-freexing solid ice when when back on the bike (if you walk through packed/deep snow in booties be sure it doesn't happen to you) So after that I decided enough was enough, if I gotta be out there all day my feet were going to be comfy! So this is what I came up with;
1 pair smartwool in appropriate thickness, with this arrangement those socks that claim to be safe at -40 are actually comfy at -40, not just painfully frostbite free. Smartwools have varying thicknesses like most wool socks, use lighter for -10 med for -25 etc
1 pair neoprene kayaking socks from MEC, large enough to go over thickest socks
1 pair Lake DH300 2 sizes too large
Feet stay warm all day. The socks are wet at the end of the day but while wearing you can't feel the diff between wet n dry w/wool beneath neoprene. I got the Lake shoes on ebay for some fraction of their actual cost. They've lasted 2 and a bit winters