It really depends on how easily your feet get cold. I know some guys who complain that even just 200 grams makes their feet to hot/sweaty in even the coldest of weather, and others who say their feet still get cold with 1200 grams. A lot of it also has to do with the right sock selection and their ability to breath and wick moisture away from your foot.
That said, I'd much rather have hot feet than cold feet when I'm out in the woods so it's always better to err on the side of caution.
And that's my two cents worth.
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