See my posts about Mayer quite some time ago. Disagree. Doesn't sound much like Dave Matthews to me(and I can't stand Dave Matthews; his voice is too nasally and sickening to my ears). Mayer's songwriting is much more jazz influenced, and his guitar playing is amazing.  I agree that he probably hasn't "suffered enough" though. Given enough exposure and time, and I imagine he will end up strung out on something, or someone, and thereby join the ranks of the tortured. Hope not, though, he looks like such a nice, wholesome kid...hmmmm one never knows.
Will have to check out Nora Jones though. Thanks for the recommendation.