More helical = more better. As above, I find that fletching noise mainly comes from ragged feathers. I always use new ones for hunting so fletch noise is a non-issue for me. I shoot big Snuffers anyhow and get the hiss from those, have never had an animal react to it as far as I can tell.
I use a Jo Jan and set it as far as I can for helical. Dad has a Jo Jan that he modified years ago to put on more helical.
I gotta think that when someone designed turkey wing feathers a few million years ago there is a reason that they wrap around an arrow so nice.....
Ryan