I would prefer to see R/EX gear only be able to slot Grade 3 and under, and not Grade 4's. That way, the balance isn't completely destroyed.

Yoshi-P has stated that PVP is coming, and we have to account for this. It wouldn't make sense if we had an Ifrit Lance with the best Grade 4 materia you could find, and it would drub the crap out of everything it came up against. That would be an instant I-Win button that people do not want to see.