Like some posters above I too have bought many hammocks--4 Hennesseys so far, some given to the kids as gifts. There is NO more comfortable way for me to sleep, even compared to a 2K memory foam mattress. But for BOBs the hammock does have sever limitations--I admit this even after over 100 nights in a Hennessey or Speer in the backcountry. Here's the rub...if you are truly bugging out you may have to sleep in a ditch, in a tunnel, storm drain, bombed out building, out in flat open ground, etc. It would be nice to think you'll be bugging out to heavily wooded areas all the time but Murphy doesnt work that way.
Now the positive. My Hennessey Lite Racer is one pound 4 ounces....at that weight penalty I can carry two shelters. The other shelter for my BOB is one of the older Slumberjack Bivy Tents-the one that is very low to the ground...and with that I carry a 3/4 length Thermarest....
OK so not all hammocks are equal in cold wether performance. If you live in COLD climates and think a hammock is for you look at the Speer and speer type hammocks and then buy the Speer Pea Pod...I've used all the underquilts available and they rule for spring/summer/fall, but for hard on winter temps the Pea Pod cannot be beat.