i bought a viper from summit a few years back and i love it. it is some work but as long as i only have on one layer and dont go real fast then sweat is a min. i have my pull rope on thats 25' long and i have it marked at 15 and 20 feet so i get an idea of where i am at, otherwise I'd be at the top of the tree before looking down ha.
i usually give the teeth a twist to the right and left to make sure they have something to hold onto before transferring all my weight. sometimes even only being in the neighborhood of 10-14feet is enough for me though, especially if there are alot branches above that height. its amazing how much more you can see only being 10 feet up. so regardless id rather be 10 feet up than on the ground with a bow.