I shoot high profile shield cuts mostly, because I like their looks best and because they fly better for me than parabolics. I wouldn't hesitate to use high profile nanner fletches either, if I had some handy.

My thoughts are that the hiss of the feathers isn't what spooks animals. How would they know it's not a fly buzzing in their ears, or a gust of wind in the leaves? I think it's the unnatural thump the string makes during the shot that shoves 'em into overdrive.