If your question is more about does 0c suck more than 5c, the answer is yes because now you need to worry about keeping your water from freezing too. But fundamentally any lower temperature is going to suck more because it's more energy your body needs to expend to keep warm, which is more calories burned, which means you now need more food too. Personally if i am able to choose where i'm headed, i would say anything under 15c is worth changing direction to avoid, and that's even with basic gear. Life is too short to spend your nights shivering in the fetal position like a cave man. But even cave men had fire and, like, a cave.
