How will you be hunting? Advice for someone who is hiking and moving while hunting will be completely different for those who go sit in a stand for four hours.
I had a buddy from Idaho come to hunt with me in MS and he said it was the coldest hunt of his life. How could that be? Because in Idaho he's walking up and down hills all morning looking for game. In MS he sat in one spot all morning and couldn't generate any body heat.
If you're sitting still for hours at 0 degrees, the heavier the better, and you're still likely to suffer some. If you're moving you can go with a much lighter garment.