Not something I would "risk my life" with, but I have used a decades older version of same, sleeping in the back of the Wally Wagon at 40 below, and it was fine; I had options available had it not been fine.That bag is a joke. Good for car camping I guess. But no way would I trust it with my life in the backcountry during the winter. Yes, there are some good 0º rated synthetic insulated bags (like the Marmot Trestles) but in practice they are about as warm as a good 15º rated down bag like the Marmot helium (which I own) but the synth. bag weights twice as much and takes at least twice the amount of space.
View attachment 37422
As I said above, for summer and shoulder seasons canoeing a 20 F rating (TNF Cat's Meow) is good enough for me. If I were going to use it winter camping, I would get one of the down bag inside an external bag from the Canadian Millitary. My wife has an ancient down bag (not military, sports and rec.) the kids used for their school winter camping trips down to about -30 C, but they had tents with wood stoves.