Bottom line is feathers are lighter than vanes. About 15 to 20 grn if you have 4 inch feathers vrs 4 inch vanes. That is where the extra speed comes from. And like said above vanes begin to take over feathers at around 50 or 60 yards because the plastic vanes have less resistance to air.

Feathers will increase your foc compared to vanes, because there is less weight on the back of the arrow

Feathers stabilize the arrow faster because they have more resistance to air

Feathers make more noise than vanes that are in good shape.

Feathers are more forgiving than vanes. Vanes are great until one gets damamged. Then they makes noise as well, and can also screw up arrow flight. Feathers can be really messed up and you will still get good arrow flight out of them.

Feathers are better with contact issues on the rest or riser.

Vanes are better if you hunt when it's nasty out.

Feathers generally cost more than vanes.

I think feathers come in more colors, I could be wrong about that though. I know they are brighter for the most part.

Is one more accurate than the other? Accuracy is a subjective thing, it depends on how well you tune your bow, or your arrow configuration. Some people can tune a bow well enough they don't even need fletching. Feathers are however a bit more forgiving in this department because they stabilize the arrow faster and have more drag. Probably not much better than vanes really. Especially if you have some sort of offset or helical to your fletching.

As far as fletching them straight goes. Most feathers have some natural curvature to them, even when fletched straight. So they would impart a slight amount of spin to the arrow any way. Plus they have more drag to begin with. Many people shoot straight vanes however with great results. It's all about the tuning in the end.

I have used both and can't really say one works better than the other. I just use feathers because I like the way they look and they take more abuse. I shoot a lot and you can really mess feathers up before having to re-fletch arrows. I don't particularly like fletching arrows. Heck I even have a couple with one feather missing, they still group pretty well with target points on.

I have a tip for you with your Easy fletch though. If you fletch one feather or vane at a time you can put the arm any where you want it. So you can put some offset into it if you want. Instead of putting the concave part on the shaft, just push it over a bit to the edge. Just make sure you do them all the same way. Oh, and you have to use some sort of fast setting glue like super glue or something. Hold it for 15 or 20 seconds and then do another feather or vane. I do all my fletches one at a time. I think it's more consistant that way. I don't care much for the arizona easy fletcher myself.

Good luck,
Paul