my main concern with a bivy is not in...
my main concern with a bivy is not in keeping me dry in a 10 hour downpour. Rather it is to protect my down bag from splashes coming off a tarp/open floor shelter/ snowcave/ dew, etc.
Problem is that I am a warm sleeper and my down bag is notorious for not breathing very well by itself. Therefore, i need to make sure the bivy sack I buy can breath really well. Does anyone know how this BD fabric compares to eVEnt or membrain? I am desperately trying to avoid the dreaded bivy condensation
The BD fabric is highly breathable and you should not encounter any problems. If you have issues you can always return for a full refund
The NanoShield fabric is significantly more breathable than eVent or Membrain.