I have played Steelfibers i80 and NSPro 850GH before on the same iron head. Both almost have the same weight.
My feel in play both shaft,
Steelfibers i80 - If you paint it silver, I will think that it is a steel shaft.
NSPro 850GH - If you cover it with some paint work, I will think that it is a graphite shaft.
I can't really compare the dispersion of shot due to my lousy skill but I can see that on 5 iron, NSPro seem a little more difficult to control than the Steelfiber.
Price wise, I will go for NSPro lah.... So much cheaper and they don't really have much different in performance with my lousy skill.