SCH even better!

[Lemuria]

Dissapation>Swiftcast>Summon

This is assuming they let you recast. Remember that this is a straight potency boost to our spells which means it needs to be significant enough to be worth doing, but also balanced which means there's a good chance we'll be unable to resummon our fairy until it's effect is gone. Further, we don't know the skill duration. It could be a hugely powerful boost but with a very tiny duration, such as 10 seconds meaning wasting time resummoning would be wasting the effect altogether.

Until we have more information speculation is all we have, but consider this. What would be the point in dismissing the fairy if you could instantly summon it with no problems?

It's like Party-Stoneskin, but stronger.

Not sure stronger is the right word. On some jobs, perhaps, but the duration is still capped at 30s. The shield bonus has only ever been as much as the cure potency, and Adlo is quite a weak cure on its own. While it will almost certainly be stronger than cross-classed stoneskin, only on targets with a lower max HP will it be stronger than White Mage's version.

Given that the Black Mage in the example had a whopping 9k+ hp at level 60, it's probably safe to assume that you'll never have a moment where it exceeds Stoneskin in normal use.