I have found serrations useful for cutting through tough clothing when you don't have a pair of shears handy, but I wouldn't choose them for a PSK knife. Serrations are easily sharpened using a triangular rod. I think gatco even has a tiny pocket sized one but I wouldn't want to have to worry about a specialized and fragile sharpening stone in the field.

My experience was helping a crashed mountain biker. She was in a lot of pain and bleeding quite a bit from the thigh, but I couldn't tell how bad it was so the pants had to come off. She was wearing sporty styled pants made of heavy polyester, like basketball shorts or warmups are these days. The material was already slick, extra slick with blood, and it was stretchy enough that it was very difficult to cut with my plain edged blade, which was plenty sharp both before and after the incident. Since then I carry a serrated blade as well as a plain blade and a pair of shears in all but the lightest FAKits. The blade I chose is fully serrated. On many of the partially serrated blades, the serrated section is so small that you have to saw, rather than being able to just let er rip.