If you're trying to keep your feet warm a vapor barrier works well, and with GoreTex you might want to do something like; boot, GoreTex (maybe built into the boot), thicker sock/pac liner/etc., vapor barrier, thin sock, foot. The idea is to keep the thicker insulation dry, which means keeping water out and also keeping perspiration from getting it wet too. For a vapor barrier you can buy official vapor barrier socks, or use small plastic shopping bags or garbage bags. Remember that GoreTex is a membrane and that its waterproof ability varies with pressure, so in some cases walking with a sopping wet boot can force water thru the membrane, heavy wind and rain can force its way thru a parka, and if it gets dirty it can loose its ability to shed water.