I'm wondering if anyone has tried the Adventure Medical Kits Thermo-Lite Bivvy Sack? If so, which one (1-person or 2-person)?

They look interesting, but I wonder if a night's stay in one would leave me drenched in sweat/condensation? Overall, would a bivvy tent, tarp, or large tarp/poncho be a better alternative? Size is important since I'm looking for an EDC shelter. Right now I'm using a 55 gal. liner per Lundin.

Well, I have carried one in my summit bag for the last year or so, "just in case". Fortunately, I haven't needed to sleep out in one yet, but, I can tell you that they are weathertight... I used one as a bear bag for my food with some para cord tied around it about 1/3rd of the way down with a flap folded over. It poured buckets one night, and in the morning, everything was dry inside.