Rack,
Not so far. I used my Akto for a 5 day elk hunt in northern CO..
Temps at night were in the 20's. Now that wasn't an extreme mountain sheep hunt either. I think if a guy wanted to use a lightweight waterproof overbag to be absolutely safe, that would be ok. The overbag could be used to keep other clothing items dry while you are away from the tent.
Now I used a piece of Tyvek for my tent footprint. Why not a piece to cover your bag at night? I'm pretty handy with a sewing machine and could make a Tyvek overbag. Hmmm.......
