I've always used feathers and never had a problem with them at all. I don't hunt in a downpour but i'vehunted in a light to moderate rain using feathers treated with gateways feather powder. Stuff works great!

One warning on the feather powder , dont get it in your eyes , and try not to breath any or get it on up your nose . Do it once and youll know why , kind of like iching powder .

I've never bothered to waterproof my feathers. In a drizzle, they will still shoot fine out to 25-30 yards. If it's pooring, I'm not shooting anyway. It's hard to track an animal when it's raining steady and I'll not risk that.