I only shoot vanes for both targets and hunting...mostly for consistency.
I use the same bow and arrows for both. I shoot Hunter Class.
The reason for me is simple...feathers WILL get heaver in damp/wet conditions. This has to change your F.O.C. on your arrows. How can that be accurate?
Vanes come in a variety of shapes, sizes and colors to match up to any shooting condition. (I biuld my own arrows).
Feathers are great for indoor targets/3-D, but for me, I do not want to keep changing my gang adjustments for different arrows or maybe forget to change...basically just a hassle.