Are feathers better than vanes for stabilizing broadheads?
Yes.
They are also lighter, which makes for a faster arrow over typical hunting distances. They will flatten and pass an arrow rest without disrupting arrow flight, rather than bounce the tail of the arrow around like vanes do, in case of accidental contact.
That also comes into play as the arrow passes through the deer. The feathers lay down and don' t offer much resistance inside the animal while vanes drag all the way through. I' ve had passthru' s on several deer and hogs that never acted like they knew they were hit while using feathers. They just stood there until they fell over. A couple even kept feeding until just before they dropped.
I' ve never had that happen with vane fletched arrows, but I must say I haven' t shot nearly as many animals with vaned arrows. Maybe the law of averages has never caught up with me.