I think when there are 1000's of zombies, the decision to shoot will be much more difficult to make. Taking a shot and drawing 50 zombies on your location would require you to use a LOT of ammo, disclose your location to anyone nearby, or relocate quickly. Regardless, there won't be much time for looting, and camping out sniping will be very difficult. Sniper takes the shot, a 100 zeds converge on his location making it REALLY obvious to everyone else where he is at. I really believe that KOS, combat logging, server hopping, all the major complaints will sort themselves out when there are hordes of zombies rather than 3.