To answer your question, all my arrows have helical fletching. And your speed loss estimate is right on the money.
As for the DNA it feels good in my hand. The shop where I bought it carried PSE, Bowtech and Elite and I was able to shoot them all. Out of them all I liked the DNA. The first year I had limited time so I set it up with the previously mentioned Rages and killed a nice 8 pt whitetail. Then the following spring I started having my flight issues when using my favorite 2 and 4 fixed blade BHs. I was having a bear of a time with it and even considered selling it until I got the issue resolved with the heavier shafts.
The DNA is fast, quiet for a bow this fast and pretty smooth drawing. Its only drawback is it has a 65% let off in lieu of the more popular 80% these days. Would I get another one? Probably not. When I am in the market for a new bow again I will likely go back to Martin or try out a Bowtech. In the past 10 years my favorite bow was a Martin Cheetah. I could shoot that bow so well that I was able to shoot 2" groups at 60 and 70 yards on a regular basis. Not all the time but often enough. But alas the bow suffered a limb crack for some reason. Martin honored their guarantee but because they no longer made the Cheetah they gave me a new comparable model which I gave to my cousin's son. That is when I got the DNA
Last edited by bronko22000; 04-22-2015 at 12:57 PM.