Arctic Muckboot are good down to about -10c or -15c I'd say, both for getting wet, and standing around in the Snow. I use them mainly for
Zodiac work, and wet beach landings, followed by walking around for a few hours in them.
Only time I got wet feet was standing in the surf with King Penguins on Sth
Georgia Islands, and it came over the top a few times. (Yes, less than ideal !)
I'm not sure about sailing grip, but they
work very well on wet rocks.
I sweat quite a bit, and havn't had any problem with feet 'swimming' in them.
I'd say their biggest issue, is over about +10c, they get uncomfortably warm.
Also getting them on and off can be a right pain in the neck. Its not something you just 'slip off when you go inside'.. I carry a small plastic thing you stand on to make them easier to take off. (Can post
photo if anyone wants when I get to the
boat tomorrow).
Highly recommend them.
Regards
Mark.