Every high speed film I've seen with a longbow using hunting sized feathers, shows the hen feather hitting the corner of the shelf/plate when shot cock feather out. Shooting cock feather in allows you to lower the nocking point and still clear the corner during paradox.
Jamie,
I've been shooting longbows and selfbows for over thirty years, and on every bow I own, I shoot the arrow across my knuckle. The old rule of thumb was to use left wing fletching(when right handed) to prevent the feather from turning into your finger when shooting off your knuckle. I've lost count how many sections of fletching I've pulled out of my finger, it is covered in scars.
I mostly shoot fletching from turkeys I kill. I strip the feathers instead of splitting, which removes the quill from the equation. I also ensure that I add a dab of glue on the leading edge of the fletching so that it doesn't snake under my skin. I do not believe that the arrow rotates much(from the high speed film I've studied) while crossing over the finger, so I don't think it matters much if LW or RW. But, I do believe that combining cock feather in along with RW feathers helps to reduce being stabbed by the quill.