Mattyv
Not a Guru by any means, but I've used these shafts numerous times. Here's what I've been using...
for "R" Flex
3 iron 1/2" Tip Trim Then and additional 1/2" for each descending club until you get past the PW. Then I go to 1/4" for GW, SW, LW.
Firm Flex trim an additional 1/2" on all clubs.
Stiff Flex trim and additional 1" on all clubs.
This seems to work for me. I've done dozens of sets like this with the GS950.
Hope this helps.