Another +1 for transparency.

I don't have the time for in-depth stat testing myself, nor am I interested in spending my time with that. Even after parsing several primal fights and instanced raids, I still don't have the slightest idea if my melded gear makes me hit any harder than my AF or if eating jerked beef is any better than eating aldgoat steaks.

Some things are easy to notice, for example increasing my accuracy for enemies with high evasion. But most of the time, I'm just increasing my stats because the game tells me to, or because I'm following some dubious testing results of people who believe hitting hundred marmots with a stick is somehow scientific data.*

But hell if I know if it actually does something - it certainly isn't visible in my damage output. That's one of the reasons why I'm currently not exactly enthusiastic about chasing after darklight gear or wasting my gil on double-melds.

* Exaggeration intended.