I am always in favor of a mentor system. Especially in a game such as this, where once you have made one of each archetype, and you unlock all eight souls within it, you can virtually have any class combo there is. But truely, it is a way to socialize and group with your friends that may not have started when you did, without being overpowering. Lets face it, if you are 20 levels higher than some group members, one, they will not learn their characters, and two, you will be passing them through content that they may have wanted to see.
Gaage - Cleric of Karma's Reprisal