Space blankets have a mylar coating which reflects heat. Wouldn't making it breathable make it less warm? It would seem like the heat would just escape instead of being refleced and trapped in by the mylar. But I honestly don't know a lot about this subject.

I don't know how well mylar really keeps you warm as a blanket, but if you have ever put a space blanket on the opposite side of a fire with a tarp shelter to your back then you will know.... it's like being in an oven.

I think this is more for usage in the 40-60F category.

Space blankets block wind and rain and reflect some body heat, but they are intended to be a compact lightweight better-than-nothing-cya item--- they have no more loft than a windshirt. The idea that any thin shell can replace a lofted sleeping bag at 43F is ludicrous and a suspension of the laws of physics.

I bought an Escape to compare to my bivy for breathability. It was extremely tight fit with just a pair of shorts on. I'm 6'2" and it was not long enough to draw the hood closed. It did feel breathable for the 20 minutes that I sat on the floor. However any benefit of a reflective coating was completely lost due to my body being pressed against the fabric. My 80 lb daughter liked it. If you are over 5'9" and 160 lbs you might have issues with it. Much tighter fit that the AMK Thermolite bivy.