ORIGINAL: bigcountry
I have a good article in bowhunter June 2004 where they tested this and found shooting thru a machine, anything over .003 makes a difference especially with broadheads.
A guy that can hit a skoal can at 30 yards 5 out of 5 times probably can't with arrows .006".
I have a Hooter Shooter (shooting machine) and while I haven't tested this scenario, I'd be willing to wager that with my spine/straightness tester that you could find the 'high' side of those .006" arrows, fletch them all in the same orientation, and
if they all had consistent spine from arrow to arrow- I bet they would group broadheads better than the .003" arrows if those had erratic spine differences.
But yes, if spine is consistent with both groups of arrows, obviouslythe more straight ones will generally perform better.