Do what you want for now, det+crit+acc is your best bet. With lvl cap going up in the expansion, my guess is t4 materia is going to be much more available and easy to get since you won't have to spend gillions on crafter gear/melds to make the gear required for t4 materia. Since you can remeld later anyway no need to break the bank a couple months beforehand.

I know Yoshi wants to involve crafters more but he involved them TOO much in these quests imo. And who's bright idea was it to make materia infusion fail when you need 75 of the buggers already? That's just redundant.

Anyway. Camp the MB for your zodiac items now, the prices swing so far between high and low that you will save yourself tons of gil in the long run if you don't have crafter friends or are one yourself.