hi
one way to find out is to get one club changed, say a 6 iron and see how you find it, hit a bucket of balls with the 6 iron before you have it changed and take note of where say 50 balls land, a pice of papper and just put dots where the balls land, then do same with the new shafted club and compare. that will tell you right off and if it works then change them all.
bill