The problem with sealskinz is half the insulation is outside the membrane, when that gets wet it transmits heat and half the insulation is lost, and keeps cold water close to your foot and keeps on moving heat away.
Merino wool is even worse when wet, they are great in the cold and dry, but when wet its the water that transmits heat away. People will go on about the naturally hollow fibre, but that doesn’t make that much difference, it just makes them 10% less worse than normal wool, and 20% less worse than cotton*.
If your socks are going to get wet something with a mix of merino and man made fibres is best, so the man made fibres can wick quickly and aid drying.
If you want to keep your feet dry without boots, the get some gore goretex socks, or even better the rocky goretex socks from america.