I will agree with the skill bonuses and that /sch and /rdm are close on saved mp but accession stoneskin isn't that useful.
Stoneskin-ga actually is a bit more useful in Voidwatch these days, where the AoE damage can be quite high (and consequently scherzo and earthen armor are being praised). In Abyssea I couldn't care any less, because I have capped -enm, capped cure potency, a whole mess of refresh, a party with very high hp, and Curaga IV spam not stealing hate (and if it does, which is rare, I can easily cure myself until hate is taken away). A 350 stoneskin on someone in abyssea, compared to their several thousand HP, isn't much. Outside abyssea, a 350 stoneskin is a bit more substantial when their HP is much less.
When you're not in abyssea god mode, stoneskin-ga can have its uses. But as pergatory mentioned, that is not the be all end all of accession. Accession has so many nice uses. One other fun use, which I've played with in dynamis (San d'Oria summoner crowd and their pets), is Aspirga on a bunch of clustered slept mobs with MP. I went from close to empty to full in a single cast. Granted that is manifestation, but same principle.
Accession can be very situational in how you use it. But I think it shines pretty well.
So, to clarify, if your 600hp Cure IV lands for 400hp (overcure), which do you get?
(A) The cost is cut by 2% of 600 --> 12mp
(B) The cost is cut by 2% of 400 --> 8mp
(C) Other: ________
Orison Pantaloons +1 return 2% of cure as MP
Orison Pantaloons +2 return 5% of cure as MP
(Throwing that in there for clarity so that people are on the same page as us)
The answer you are looking for is choice B
If you cure for 400 HP in Orison Pantaloons +1, it will essentally reduce the mp cost by 8 (the 2% of 400). The maximum cure does not matter; it's instead the actual value that is cured. So if you were WHM/RDM instead of costing 88 MP the spell would cost you 80.
If you were using Orison pantaloons +2, it would reduce the cost by 20, costing you instead 68 mp.
Similarly, my Cure IV does around 600, and my cure III does around 300.
If you used a cure III on that person, you would have saved 15 MP and paid 31 MP for that cure 3.
You could use a capped Cure 2 on them if you really wanted to for 19 mp, resulting in a total of 50 mp (and saving 18 mp over the cure iv)
By avoiding overcuring and using Orison Pantaloons +2, you can save a whole mess of MP over time. I always wanted an effect like what they do, and I feel they are an incredible addition to white mage's arsenal. Especially when you use spells like curaga. Edited, Jun 14th 2011 6:38pm by Annalise