Martinez hasn't been significantly hurt since he went to middleweight, and Chavez does not have concussive power in this division, despite whatever HBO may tell you. This doesn't even take into the account that Martinez is loads slicker than Lee.
Good experience for both guys. Chavez is too reliant on his physical strength. That will backfire eventually with a big puncher.
Lee is game.. but he's losing confidence in his ability to win it seems.... Unless he's trying to save energy for the later rds.