Your main stats are considerably lower on the 510 vs the 530, it’s a loss of 41 int. Weapon damage >>>> main stat >> substats unless you are certain jobs, and this mostly pertains to healers when it comes to piety. Healers have such strong mp recovery tools than unless you’re spamming aoe heals or raises you should not run out of mp, making piety entirely useless. Piety is a prog/comfort substat, I personally prefer melding it if I’m going to use it to replace once I get more comfortable with the content.

Also, crit is king for nearly every job except blm as far as substats go, blm only gets more benefit out of spell speed because of how long their cast times are on their nuke, allowing them to go through more cycles in a given time frame.

Generally you only want to min/max substats when you’re at max ilvl, and generally to hit certain stat breakpoints. So you’ll want a mix of 530 savage gear, 530 tome gear, some of the 525 zadnor gear is pretty competitive or can be used prior to getting a better 530 variant, or for certain jobs (like healer again) a 520 augmented crafted ring because the 530 tome has piety.