Bear in mind that a certain degree of what you do is down to the playstyle of the individual as well, and some of the rather Elitist people in the EJ forums will state something as an absolute when they haven't tried many of the alternatives. That said, however, their maths and theorycrafting is sound and solid and is at the very least a very good source of information.
I laugh in the face of the guy who made the mage thread and says that all mages should be fire and that a Fire/Icey Veins spec is the absolute best... I recall beating Tenuviel on damage by a massive margin with my lesser gear and supposedly "less viable" spec