The wisker bisquet rocks. been using one for two years. and am paper tuned with perfect bullet holes. and can shoot my knocks off at will from 20 yards. also i use a string loop and it performs as expected.
As far as getting good groups its all in the setup and the shooter. the biggest part of the setup is properly spined arrows. If they are, then set up is a breeze and perfect flight can be acheived even without vanes.
yes the wb does wear out but replacements are cheap. I also shoot feathers and after about 1000 shots with the same arrow you can see that it is taking its toll on them but if they are fletched properly they ought to be good for another 1 or 2 thousand shots.
so to me id say the pro of having a rock solid dead simple arrow rest out weighs any of the cons ive noticed
just my 2 cents
Bob