http://dmmclimbing.com/knowledge/how-to-break-nylon-dyneema-slings/ Obviously, they are talking about climbing situations in the video, but the information is equally applicable if people are thinking about using slings as cowstails on their harness (either for SRT or just for protection on 'easy' traverses).
It may be worth pointing out that the test method in the video with a rigid test mass attached directly to the sling is the worst possible case. A person in a harness provides some opportunity for energy absorption, so the actual peak forces
may be a little lower than those mentioned in the video. However, they are still high enough to do serious damage to the person.
Dave