I tried it once or twice. Did not give it a fair chance but my bow was loud, it was awkward, can't shoot 3 under, my eyes won't focus on the arrow,, I really don't think I can focus my eyes on it, my bow tune was way off, again my bow was loud, lost arrows and did not like the "mechanical" aspect. It's kinda the reason why I don't like a compound with sights. But I'm sure a practiced FC shooter would whip me badly on a 3d course. Being a some variation of a split vision/instinctive shooter I go through swings of great shooting where I can not imagine any method better than mine to periods where I'm not sure if I could hit a moose at 10 yards. Those time when I'm not good are when I think I should try fixed crawl.
I am thankful that most of my shots on deer come quick, in the woods, there isn't much time for anything but draw and shoot, I don't get much time for alignment and luckily shoot best on those deer. In Wyoming where I hunt whitetails each fall the shots at a deer standing in an open field are a real challenge for me. FC method would work well for that kind of hunting.
Tedd