I can tell you that a Project x 6.5 is in between a stiff and x-stiff.  Now much of a difference it really makes, i have no idea.  I play the 6.5's in my irons and i also have a 6.0 in the 2 iron i just got and I cannot tell that much difference at all.

For the graphite shafts, I have no idea.  I only have a graphite in my driver, so I do not have much opinion on that.

Joey