Scholar rant.

[technole]

I prefer not to have to switch fairies mid fight.

You can't have that mindset as a SCH in end-game raiding. Everything is situational. The switch is mainly to push DPS in phase 1 as everything is practically double damage for 0.5. Plus you can strategize these situations around eating your fairy for immediate Aetherflow, which also opens a window to re-summon as a different one. You don't have to use Dissipation, and can just swiftcast the change as that is how it's usually done.