RyukenAngel said:
I think that the Role system is going to seriously reduce the 'zilla'-ness of any class, so long as it is stuck to.
There's a lot to balance between roles. Defenders may prove to be far more useful than Strikers, or vice versa. In nearly all previous editions of D&D, strikers have excelled, whether Leap Attacking Shock Troopers, pouncing druids, TWF rogues, 2E's twin-longsword fighters, or ray-specialist mages with sudden metamagic feats (Enfeeble, Exhaust, Enervate). Most useful against the BBEGs. That role -- being optimized for taking on one tough target -- is always going to be valued.
The effectiveness of the other roles, I would imagine, will depend on the kind of games that are run. The "core balance" is going to be for a game that uses minis, has a certain level of terrain-based features, has a certain balance of "minion" encounters and "elite" or "solo" monsters, and has a certain party size. Look at 3.5; a bard was WAY more useful if you had a druid and a TWF rogue in the party than if you had a cleric and a sword-and-board fighter.
I would imagine that changing certain assumptions would make Controllers more valuable, while changing others would make Leaders more valuable. This was true in 3.5 as well, with adventure design and gaming style affecting how powerful various choices were. Minis-free game? Good luck with that spiked chain specialist. One big fight each day, generally on the PCs' terms? Get ready for the casters to dominate.