To begin with. T13 parse is stupid. Too much DPS results in a painful death before dive bombs so you have to stop.
Also, you can swap as many crafted piece you want to gain stats and it might end up being an overall single target dps gain, T13 has a long AoE phase. All the intellect you trash hurts your AoE. In an AoE situation spellspeed offers nothing.
In T13, everybody will tell you the hardest phase is the adds + divebombs. You want to get rid of these mobs asap.
If you want me to be more direct then I can... I respect Puro's work and he's an amazing guy. But his stat wights and his calculator has one major flaw. It's set for a single target fight. This is not the case for 3 out of 4 FCoB fight. This means his calculator is correct but doesn't represent the reality. I used to follow those numbers by heart and one time I randomly added more crit to my set and my DPS gain was enormous in T10 and T12.
If... you want something more solid for a proof. Look at the e-peen T12 kills numbers on his sheet. There's some BLMs that did 590 DPS. This is incredible damage. I also took a good look their encounter took 2 more minutes than my own parses meaning they are most-likely selling T12 to someone and they are doing this with 7 people while having the seller do nothing but live in the last phase. This means more Bennus and more flares. This also means 2 blackfires that they possibly Flared instead of letting the Scholar dot bane kill blackfires which is smarter DPS.
Also, in T13 again, the only way to get a huge parse is having people die so you get more AoE in the AoE phase. The ultimate way is to sell T13 with 3 DPS only and have Ninja + Bard + Black Mage. You'll get all benefits of having all the Foes since the Bard will get Goad all the time and with down time, ninja will never run out of TP so no Peon.
I will also post my T11 kill this week with the BiS I did with no crafted and I did 555 DPS. You'll need to take a good look also that I use Augmented Hat + Gloves because Dreadwyrm Gloves has yet to drop for me.
The one and only true turn to check your single target DPS is T11. It's really good since it's a skill check to keep your casts while moving, other turns are at risk of DPS inflation. Another example is my own T10 kill with 583 DPS. I had Augmented Ironwork Staff at the time. I didn't limit break and AoE phase was longer. I can also tell you I only had 600 Spell Speed and I could have got more but I invested in Crit and Det for that phase. The ultimate proof is Lucrezia's speed kill and the way they did it. They stacked all adds together since they could live the extra damage. Even with Limit Break, their Black Mage did 620 DPS and he had more crit than spell speed. They also did it much faster than [CL]
Now... I am aware everybody have their own concept of BiS. This one I posted requires no crafted piece. I did put one for T11 with 3 Crafted Items and it's probably not the best. It's just an example.
Looks solid ;o It's a lot of materias lol
Seems like you're that guy that did 590 in T12. I'd like to see a video to see if your set is truly that amazing or there's elements in the fight that were used to help your DPS.