Good topic.
I am 50 this year. Was playing PRGR M43 irons for last few years and going fine, but was always a bit balloony in the wind. This year shifted to Project X LZ 6.5 (125g) 4-pw and scores have been noticeably better.
The shaft is heavier but loads and kicks. Bit less spin. Certainly doesn't feel like a 6.5 flex.
Now this has made me go "all heavier" - 70g driver, 76g 2w (Baldo Brassy), 105g 19* hybrid, 125g wedges (ATTAS 125 Spin)
Maybe this will do me until 60!!!!