prime example: my old irons we dci 762's. dg s300. played well with them but had low ball flight. 2* stronger lofts than my ap2's. ap2's kbs tour stiff. hit them higher, farther and with more spin. like I said, too many factors involved in shafts, weight is a big one. the dg s300 were a lot heavier than the kbs ball flight a lot lower with dgs300, but both were stiff flex.
if your looking for the proper setup for your game, let the pros do it. go get fit.