After going through the reputation rewards given by the various factions in cata, one thing is blatantly clear: Blizzard has cascaded gear amongst the factions in such a way that classes that get a great item at Exalted, probably won't have any items to pick from at Revered! This is clearly done on purpose to encourage players to get rep with all factions.
As an example, a new level 80 player that starts leveling in Cata has to choose between Hyjal and Vashj'ir questions. Chances are, the most obvious choice would be to choose Vash'jir since reputation gains in there lead to an amazing DPS ring at exhalted. However, there is nothing at revered... instead, the good revered gear is held in Hyjal!
It is in my opinion that players should first focus on aiming for revered gear first. You need ~21k reputation, versus ~42k. Not to mention, the you will be boosted by the quest reputation. Then, when you are 85 and dungeons become your main grind, it should then be when you turn to get exalted.
This strategy may not get you the pre-heroic BiS items as quickly... but it will gear you better *overall* much quicker. Quite simply, I rather have a character that has a lot of 'great' items... versus one that has a lot of decent items, than one BiS.