I've shot feathers for about 30 years (vanes also at times) so have a little experience. Feathers can be noisier due to rougher surfaces, especially when they get chewed up. They can get soggy in the rain and lose steerage (but you can get waterproofing for them now). On the plus side you'll gain initial speed of approx. 5fps, assuming 4" being used, because three 4" vanes weigh about 25 to 37 grains, depending on which ones while three 4" feathers weigh about 10 grains. The additional effect of this also is better FOC, which often helps with arrow grouping. They will stabilize an arrow quicker out of the bow, especially important when shooting broadheads.
Right or left helical doesn't amtter so long as you get the right ones for your jig, or specify which you want. Doesn't matter. To keep the points tight just use bowstring wax.
So now you got some plusses and minuses. Now go try 'em and see what you think.