Firstly I am not going to argue about what I did or didn't do 10 years ago with someone who wasn't even there.

secondly I can tell you that you will not 'fine tune' 5% more speed out of a rig by altering diamond/spreader settings from those I have given or those your sailmaker will give you. 5% is the kind of difference made by whether or not you put your jib up, you will do well to find 1/4 % with fine tuning spreaders.

My advice is my honest opinion based on thousands of hours of two boat tuning with the best sailors in the World and hours of dinghy park chit chat with them.

Eric give what I say a try, if it doesn't work it won't cost you anything.