The question is do the vanes produce flight-performance, grouping, and accuracy to such a greater degree than other vanes as to justify the cost? In bowhunting, 1" off mark is not a whole lot to fret about. How tight are the groups when 1" off mark?
IMO, bowhunting is a game of inches. If quickspins shrink my group sizes by an inch, I feel like I owe it to the game I hunt to take advantage of that technology. And for me they do. Since switching from 4" feathers to quick spins, my groups have shrunk considerably. That doesn't mean everyone will experience the same. Add in a little buck fever, sub freezing temperatures and those 1" off the mark shots can soon become more like 4". I am always looking for any advantage to improve my accuracy, even if it is very minor. Because it is the combination of many things that will make me as accurate as possible.
It never ceases to amaze me how people will spend $750-$1000 on a bow rigged out, but then won't spend a few extra dollars on better vanes, broadheads, arrows, etc.... to give them an additional advantage. JMHO