Gary,
I'm 10 years younger than you, but I still don't understand fully why my fitting for my Ping irons (i10's) last year resulted in switching from regular flex to stiff. I really didn't see any appreciable change in carry yardages; btw - my yardages are very similar to yours. The one thing I do know, with these shafts, these irons feel much heavier.
But back to your question, accuracy and yardages really didn't change much for me. And despite playing/practicing less, my index has actually gone down a few points since changing to the new clubs.