Just how different are the 13 jobs with regard to secondary stats?

[Lufir]

Totally wrong. In most cases: 5 critical hit rate = 1 str/int/dex

In Black Mage's case: 3 spell speed = 1 int. Black mages that stack spell speed have a significant advantage over those that don't.

Uhh no. Crit relies too much on rng to make your statement true.