I think it just takes a larger amount then what we're using. Be honest with yourself. Do you see a huge difference in damage when you add str+21(via rings)? Or Atk+30? Someone who did a huge test using these amounts so a difference of at most 10 damage. Now Consider this, the materia can go in two slots, weapon, and feet. It caps at +30. So if you're using +20, when youcan quite easily get +60(okay, not easy. The element materia only comes from weaposn) you will probably not see a very large affect. It also seems SE wants us to multi-bind, or they wouldn't have even added it. So if you were just to double-bind both of these once, you're at 120. I think you would surely notice a difference then.