I have used them a few times over the yrs, but for me to use one, it has to be SUPER cold and even then, you can have issues with the propane flowing well, as it will freeze too!
many times you really need to shake the can's really good to get them to ignite and or stay flowing!
seem to work better if kept upside down, and then flipped before using!
you also have to make sure the blind is venting well enough to safely use them in side, windows be open good for cross flow!
and another thing to think about is NOISE< or scent!
they can make a bunch of noise IMO
BUT when your in cold enough tempos I doubt you care about the noises
the good part about a well insulated blind, is you DON"T have to run a heater non stop
and I will ad this too, I have used real small propane heaters heaters in pop up blinds and had deer within feet of me, but as in life, NOT all deer react the same to things, some will be more curious, some just won;t seem to care and well, some will AVOID a area they smell something new or strange!
BUT if the cold gets too much and you go home, or cannot sit still, doesn't matter as you won't get a deer while at home, so longer your out there, even with draw backs, the better your odds are IMO!
just turn on, warm things, and shut off