Stat priority for a red mage

[M1551NGN0]

I am sure that it is Crit > DH > Det> SpS. I read it off somewhere but I can't for the life of me remember where exactly.

[TelosNox]

If Nemekh's spreadsheet is correct:

1000 CRIT = 104.95%
1000 DHIT = 104%
1000 DET = 104.2%

1500 CRIT = 107.76%
1500 DHIT = 107.2%
1500 DET = 107.2%

2000 CRIT = 111%
2000 DHIT = 110.35%
2000 DET = 110.2%

So we clearly see: CRIT is the best Stat (even in low tiers). Followed by DHIT and DET which switch their positions at about 1500. Lower DET is better and higher DHIT is better.

Question is: Is that spreadsheet really correct?

[Kitfox]

Yes, but stats on gear never go according to customized optimal distribution, so you have to consider the whole gear set and the available stat combinations to tell which is best at any given moment. Job mechanics, party composition and stat tiers also play a role so there's usually never a straightforward answer without simulating the rotation and using full damage formulas. If you go really deep into the rabbit hole, you'll find that it's possible to build encounter specific gear sets, but that's a land no sane person walks upon.

[TelosNox]

You still can prefer CRIT in general

Possible combinations:
CRIT + DH = Perfect
CRIT + DET = Not bad either
CRIT + SPD = Ok here we might consider something else but first we should check: Is SPD the major stat? Or is CRIT the major stat?

If you see CRIT + SPD then what else is available? For casters it's currently most time DH + DET.

http://ffxiv.ariyala.com/16ZIA
This is my current gear which I considered as BiS for SMN so far. You could avoid further 125 SPD by switching feet.
We can do some math here (expected dmg multipliers):
2085 CRIT = 1.116064
1727 DH = 1.08625
1498 DET = 1.072
Overall = 1.29961

With other feet
1987 CRIT = 1.109251
1772 DH = 1.089
1676 DET = 1.082
Overall = 1.30703

So average DMG per Hit would be higher.

Now we consider SPD
457 SPD = 1.005
582 SPD = 1.013

So if we multiply with speed:
CRIT Feet: 1.013 * 1.29961 = 1.31650493
Other Feet: 1.005 * 1.30703 = 1.31356515

Now it depends on how much SPD affects pets. Do they gain dmg by SPD? If pet is not affected by SPD at all, then CRIT Feet are a dmg loss because 30% of caused dmg is not affected by SPD. If pet dmg scales with SPD then only about 10% (Fester) of caused dmg is not affected and the CRIT Feet are a gain vs. the others.

As we are talking about RDM it is more clear:
Skills not affected by SPD should be Fleche, Contre Sixte, Corps-A-Corps and Displacement. That's about 20% of dmg done. So SPD only affects 80%.
According to this we adjust gain by SPD as follows:
CRIT feet: 1 + 0.013 * 0.8 = 0,0104
OTHER feet: 1 + 0.005 * 0.8 = 1.004

Overall:
CRIT Feet: 1.0104 * 1.29961 = 1.31312594
Other Feet: 1.004 * 1.30703 = 1.31225812

So CRIT feet should be better here for RDM.