I carry plain edges almost exclusively, and agree that at least some people who swear by serrated performance simply haven't learned proper sharpening strategy. However, I think the reaction to serrations has gone a bit too far, and people are more down on them than they should be.
In my experiences, serrations do seem to cut longer, work better than plain edges (even properly sharpened ones) on harder objects, and do a very nice job zipper-cutting objects whose diameter is much smaller than the diameter of the serrations.
I think serrations typically work based on three features. First, they are typically chisel ground to a very thin edge. But this isn't unique to serrations -- good plain-edge sharpeners have always sought thin edges for performance. Second, the inside of the serrations are little hooks, presenting a constantly changing angle to the thing being cut. So even when the insides dull a bit, for format reason alone they still cut. With a plain edge, one can swivel one's wrist to change angles, to somewhat simulate this.
Third, and perhaps most importantly, serrations have peaks. They may be round, like Benchmades, or sharp, like Spydercos, but they have peaks. The three features of the serration work together. The serrated edge is laid down on the object, and pressure is put on the peaks, which sink quickly and easily into the object. This is akin to someone stepping on your foot wearing sneakers (plain edge) or high heels (serrated edge). The points on a serrated delica penetrate deeply, immediately. Once sunk, the curved, ultra-thin-ground valleys cut their way through on the slice, and as you go through the points keep penetrating downwards. On top of that, the points seem to take a lot of the dulling, leaving the valleys sharp -- with a plain edge, the whole thing gets dull with every cut. And even when the serration valleys start dulling, the hooks still seem to cut.
Grind your plain edge thin and coarse, and it can approach serrated performance. On soft rope, it's not too hard to match or beat serrated performance. As the rope gets harder, you'll see serrated performance start to pull away.
I still believe a thin, coarsely-ground plain edge is the best choice for me. However, someone cutting hard plastics and the like might find serrations work better. Anyone having trouble sharpening, or not keeping their edge thin and coarse, will definitely find serrations working better.
Joe
