have to say that when I have had tight stuff on my lower legs in cold temps, it makes me feel colder for my feet. It seems to me that it restricts my blood flow, so thats my take and experience with it, I know I wouldnt want compression socks on while riding. just me.
kinda like warm socks in boots, or even my bike shoes, looser is warmer for me (especially with my shoes and temps of near 0 c )