Quote Originally Posted by Fyce View Post
Check that Reddit post.
They did a pretty good job at pulling the stats out so they could go with some recommended infusions.

That theory craft was done in order to know exactly how many bonus stat you could squeeze out from the Relic upgrades (Nexus and Zodiac) and at which breakpoints.
With that being said, I don't think a single point of det or crit are worth buying any Tier IV materia unless you're rolling around in Gil like Scrooge McDuck. The amount of extra damage it brings is barely noticeable, especially on a tank class.