DO use real tent pegs to hold the thing down. I put one up one night before deer season opener, when it was windy and blowing a light rain. The ground was pretty soft, and the wires provided by Ameristep were not enough.
Opening morning, I got to my blind location, and it was gone. The wind had blown it over the hill and into my uncle's yard fence (I was up the hill and in a large pasture from my uncle's house). I did recover the blind, unharmed, but it was a lesson learned, stake it down solidly.
I DID kill a nice big buck out of the pasture that morning, sitting in the chair that didn't get blown over the hill, but I was wide open, and the deer was preoccupied with the does he was traveling with. One shot, about three leaps downhill, and the buck was piled up.
