Hey Arvin, I've never been into flight shooting, but I can see there are a lot of things that could slightly change the outcome.
It seems to me that stiffness can have opposite effects at the extremes. The sooner the arrow quits flexing the less drag, but the stiffer the shaft, the more friction there will be at the arrow pass. There is probably a sweet spot somewhere in the spine range.
The same kind of balance is at work in the feather size/shape question.
Have fun testing. 8-)
