I think it's more of just small abilities that support or fit the playstyle in some way, rather than different weapons having different stats for each class. The Titan's style is a lot like the Master Chief. He can run in, smash the ground, knock some people around, kill a couple with his assault rifle, finish one off with his fists, then step back just a little bit and hide behind that tiny rock to regain health. The Titan isn't the type that stays back much. He's in the battle, fully aware of where every bit of cover is, and knows just the right time to take cover before heading back out and dealing a lot more damage. He runs in, kills people in a badass unstoppable manner, ducks behind cover to reload his weapons and recharge his health, then hops out and gets right back to it. To me, the Hunter- at least in open combat- is about staying a bit back and using that sexually attractive revolver of his. He doesn't use cover as much, but since he's a bit further away he can move around and make himself a difficult target to hit. And since he's an excellent marksman, his job is about lining up that shot and taking guys out with as few shots as possible. I don't think the Titan is so much of a Tank, as he is... more of a "brutal infantry" character.