Slap some vanes on one arrow and test shoot it. Every bow is different. I can shoot wet feathers with no loss of accuracy which undoubtedly has a greater weight effect than the difference between feathers and vanes. I would suspect if your tuning is spot on it won't make a hill of beans difference for you.
I've got my arrows tuned so well that I don't need feathers at all to hit what I'm aiming at. I can slap a big ole Grizzly broadhead up front, completely submerg my feathers in a bucket of water and swish them around, nock it, and it'll shoot true out to 40yds (the farthest that I have tested)...that's good enough for me. I now just use plain ole turkey feathers, I don't treat them for waterproofing or anything, and I hunt when I want to without regards to weather or worrying about my tuning being off.