With Stormblood only a month away, save the materia. This game is strict vertical progression of gear. Your i270 gear will be useless by the time you reach lvl65 at the latest.
Now, if you have not purchased and are not going to purchase SB, then I suggest tinkering with http://ffxiv.ariyala.com/. Crit > Spellspeed > Det is (or at least was) the recommended order of stats boosts. This is after you have hit the Accuracy Cap for 3.4.