Honestly, I don't completely understand it.
From: http://vanitstudios.com/smforums/viewtopic.php?t=139
Druid:LOW
Hunter:LOW
Mage:LOW
Paladin:MEDIUM
Priest:LOW
Rogue:FULL
Shaman:MEDIUM
Warlock:MEDIUM
Warrior:LOW
Does "LOW" mean you don't need that certain class or do you need it as you're low on that class?
Also, how often is this topic updated?