I'm a believer in arrow calculators (I haven't used Stu's, but I often use the 3 Rivers Archery one that I believe he helped build), and have had excellent luck provided I entered correct data. Of course, we're talking fairly common components - bows, arrows, tip weight, etc. I think people who have more eccentric tackle may struggle a bit with them. On a side note, I went through a carbon tribulation a while ago (part my stubborness, part carbon's tendancy to stiffen quickly) that caused me to abandon the carbon endeavor altogether. Haha