Gentlemen there is quite a BIG difference when it comes to feathers or vanes, my uncle and i have experimented with both the conclusion was,

using feathers results in higher arrow velocities, greater stability, better guidance, higher accuracy and more forgiving flight. You get less fishtailing from the arrow, Feathers weigh less than plastic vanes, when feathers travel over your arrow rest they also produce less friction resulting in a smoother launch and faster speeds, depending on your set up you could get up to a 5 ft/sec gain.

everything has a downside, with feathers, you need to keep them dry, so if your hunting and it starts to rain, be sure to cover those babys up.