Bones-There is comfort in the knowledge that you have the required materials for fly tying. Personally, I will use anything that I have aquired if the fly calls for it. Furthermore, I am prone to use Cree as a substitute for grizzly because it looks as good or better and hopefully the fishes agree. Case in point-I am in a Salt Water Surf Fly Swap and will tie 24 identical bugs: all having a wing made of a matched pair of cree Hackles.

I like LadyFisher's attitude towards to good stuff