RE: 4 or 5 inch vanes?
Im not tryin to change your mind in any way. But, an option. Go to feathers with your carbons. First off, they'll stableize your arrow in a matter of feet instead of yards like vanes. Second, if u do hit somethin with your arrow or fletching, the feathers will straighten it out much faster than vanes. They make broadheads fly so much better. With the carbons, your probably shooting more speed, if your not use to that speed then feathers can help straighten out radical misses(they did me). People say feathers are louder, it doesnt matter if the deer hears the arrow go past him. Stand down range and have someone shoot a feathered arrow and one with vanes. Feathers will sound different with more of a woooosssshhhh to them, but vanes have a low rocket type sound. There both loud. Another thing, feathers are cool lookin :-) u can customize more with them. And about them gettin wet, a couple drops of rain or huntin in mist wont hurt them, if its pouring put a bag over them or dont. THey shoot pretty good wet.
This is just my opinion on the subject, if u stay with vanes, stay with 4 inch slight offset.