Knowing when to switch your main class?

[Cynfael]

BLM is easy to learn and tough to master. You have to really abandon the notion that it's a rotation strict class in order to excel. The best BLMs out there realize this and can stay on top of their mana consumption while moving and keeping their IIIs up.
It's more like a weave when done right and don't go falling into those silly guides that tell you there's only one/two ways to play your class. Those are there to guide yours first steps on 50 but are ultimately limiting if you put too much faith in them.

This is a very good point.

BLM appears from the outside to be a faceroll class that inflicts respectable damage with a simple rotation, has infinite resources, and has only one glaring weakness (movement).

In practice, the complexity of BLM play is not nearly so much in the buttons you press as in your own judgment, planning, sense of timing, and even "twitch" ability. Movement alone is rarely that big of a deal when you cast-clip, use defensive cooldowns, and AM properly.

The difference in DPS between a good BLM and an average BLM is HUGE even though they could both be doing basically the same rotation.