Ok I'm going to through something different out there. I use coyote fur. Just because I had some laying around. I have found that it really doesn't matter. If you have your nock point right your shelf material shouldn't wear out that fast. I have had coyote fur on my longbow shelf for a year now and it still has alot of the fur left on it. I have used just soft leather also, so even if the fur wears down the soft leather does the right job.
I also use coyote fur strips in my string for silencers. Same idea, if the bow is tuned and silencers in the right place it really doesn't matter a whole lot on the material.