With their promise to reward player innovation and creativity I have heard some worry about the class balancing. Which can be a real big issue in an MMO. I have heard of many times where a class will be completely ignored because it has such a large disadvantage due to being a close range fighter, or just not having a good enough DPS.
Maybe a good solution would be to base each class on a different situation.
Some examples would be if fighting a heavily armored enemy, such as a crab, you would do more damage as a Marauder, than as any other class, or if fighting a fast lightly armored enemy, like a Marmot, Pugilist would be the best option. Fighting Multiple enemies would be a job done best by Lancer and fighting element based enemies would be best handled by a conjurer.
By giving each class a specialty they give them all a role to play in raids and parties. It adds a great amount of strategy as you would have to think of how to equip your skills as well as build your party to cover your weaknesses. Because then you could party with a few classes, like a party of 3 archers, 3 gladiators and 2 healers. But in situations against heavily armored enemies or swarms of enemies you would have a major disadvantage because you have nothing in your party for these types of situations. If you had a lancer then maybe your party would not have been overwhelmed by that swarm of mobs, or if you had a marauder then maybe you would have been able to do enough damage to kill that large mob before it wiped your party.
Situation based class balance gives the options and strategy of combat to the players, while avoiding Parties only taking one or two classes because the other ones don't have any compared to the others.
Edit: Well after seeing everyone's arguments as to why this system would not be the best of ideas, I no longer support it as a main system for balance.
But as a system to encourage diverse parties and an added layer to the strategy, what do people think?