Interesting variety! I have been using plain leather (deerskin) and never noticed it being loud. On my longbow I just made the shelf and shield from a single piece of leather. Recurves usually work better with a separate shield and shelf due to the sharp angle where shelf and sideplate meet.
I couldn't get as good arrow flight with sealskin on my longbow. My son's Herter's recurve likes it though.
Something in me just rebels at the thought of sticking velcro on a trad bow. I know, fiberglass is not all natural either, but it's a personal thing.
Beavertail sounds intriguing, but the back of a worn-out deerskin glove is a lot cheaper.