I used to do a lot of rock climbing too. The most dangerous fall we could take would be if we hit a ledge or the ground (obviously). However, the next most dangerous fall was one that was close to the belay, before enough rope was fed out to cushion the fall. The forces of stopping abruptly after 6' or so of freefall are severe enough to break bones and dislocate joints. All the falls you would be likely to take from a tree stand would be in this second danger category. All harnesses that I know of that are specifically designed for tree stands have built in screamers, meaning webbing that is sewn together in such a way that it rips apart when a hunter falls and cushions the impact. Climbing harnesses are designed for longer falls, where this isn't necessary because there is enough rope out to cushion the impact (unless you hit a ledge, of course), or your belayer is hopefully going to ease the brake on to accomplish the same purpose. So if you're going to use a climbing harness for hunting, be sure to buy a screamer and build it into the system, since it won't be an integral part of the climbing harness.