Re: Wooly Bugger or Crayfish fly?
Dan, IMO buggers & crayfish specific patterns both work for imitating crayfish.
Buggers can imitate many things that various fish species eat. As long as you weight them appropriately for the waters you intend to fish, & get them near the bottom, they'll work fine.
However, for my own purposes, I've gotten away from tying anything but simple patterns for crayfish. Most of what I now tie are adaptations of "flats" type flies popular with Bonefish or Redfish anglers. These type patterns are often used to imitate various shrimps & crabs, and many resemble crayfish in general shape.
Patterns such as the Squimp, tied in crayfish colors are what I now use, and they've worked as well as the more complex crayfish patterns I've tried and are much easier & less time consuming to tie. I no longer bother worrying about shell backs or 2 claws on a pattern. I've not found that the fish care either way, and as long as they eat the simple patterns, I'll prefer to tie them.
Remember, no one likes to be behind the big truck, but that's better than being under it!