Serrations will continue to cut cardboard and rope after a plain edge has stoppoed cutting effectively. Serrations have more surface area, and they have sharp points that can initiate a cut. They are very useful if you have to cut anything like a steak or other food that is on a plate, as only the points of the serrations are getting dulled by the plate. The serrated edge also has multiple angles of attack for the edge to cut something. The serrations may be ripping on cuts when they get dull, but they do cut better than a dull plain edge. They are harder to sharpen, but a Sharpmaker can easily get serrations tree topping sharp or better.
All of that was just being devil's advocate because I am a PE guy, but I don't think the benefits of serrated edges should be ignored just becuase we like our plain edges and their cleaner cutting and easier sharpening better. A very sharp plain edge can probable do everything a serrated edge can do, but unfortunately hair whittling edges go away quickly. I will have to test my SE Endura Wave against a PE knife of the same steel to see for myself how each does. I just remember being shocked how long and how well a SE Caly 3 I used for a week in a passaround cut. It seemed like it kept on cutting way after my PE VG-10 knives would have given in. It might not have cut as clean as a PE, but it kept on effectively cutting.
Mike