The way to seems to work is that it counts the stat bonus from the item before the requirement. So if your helm loadout is +8, but you end helm is +12, you almost have 4 more.

Also, what is the order of item equipping in loadouts? I know the helm is first. Maybe the weapon is second, etc...

Edit: why fix it exactly? It promotes a feature that makes the game that much more diverse and fascinating.