I've had both C/F and off the shelf. I am pretty sure if you have the right shaft for your own swing then it will improve the performance but if have inherent swing flaws (over the top, lifting etc) then C/F will only go some way to masking these to a degree. If I buy another set of irons I will look at C/F as I think there are plenty of better shafts for me rather than the True Temper R300 I have at present. However as I'm still making swing changes I can't see any point getting a fitting at the moment for a swing that may still change in terms of path etc