The Black Mage Rotations

[PessimiStick]

So I guess I have a basic BLM mechanics question: in terms of mana recovery, is the 2x B2 necessary to guarantee a reliable MP tick sufficient to begin casting the F3? Because it seems to be that if Flare blows all your mana, it doesn't matter how much you re-enter Astral with, and could get by with 1 B2 cast as long as you are able to cast F3.

Or is that really to wait for the Transpose cooldown?

Partially Transpose CD (12s, or ~5 GCDs), but mainly because you only get the cast speed bonus for UI3. If you only Transpose --> B2, you're hardcasting F3 and Flare.

It will do the same damage (UI doesn't reduce the damage).

This is not correct. Fire spells deal 70% damage under UI3.