I started using these about 15 years ago as a result of a recommendation in a Feather Craft catalog. I use them for just about all my size 10 - 16 dry flies bodies, and think they work great. When used in conjunction with a rotary vise, they are a breeze to apply and look great. The fish seem to like them just fine.

If there is a downsize, they are probably a bit more fragile than a dubbed body. When they get too chewed up, the "biot" breaks and starts to unravel. At that point, not much you can do other than tie on a new fly. But to put in context, I usually can get 20 - 25 fish from a single fly, before it's time to recycle it.