For me the advantages of a banana feather is the visibility of the arrow in flight. I shoot bright yellow fletching, and I LOVE to watch the "ball of yellow" speed toward the target.
Banana's probably slow your arrow down slightly compared to Parabolics, or Shield, but I doubt its by much.
I in my experience banana's can make more noise then other feathers.
Over the years, I have shot all types of feather cuts, right now it's 3 X 5.5" banana's. I've always wanted to try 4" banana's and now I have found a source.
chris <><