I just attended GenCon Indianapolis 2011 with the robot. Over the course of the three main convention days (Thursday, Friday, and Saturday) I took the robot from fully charged to fully depleted batteries five times without a single mechanical failure - a new record, and actually quite astonishing considering I'm still using $12 cheap import servos. This translated to over two hours accumulated time walking the robot around the convention and entertaining the crowds.
With the new 60mW Xbee Pro radios I did not have a single incident of control failure, even when the robot was 30+ feet away and surrounded by people with cell phones. I didn't even need to use the external antenna on the robot itself.
The MG996 servos held up well, but a few are starting to sound rough. Quick examination reveals that while most of the MG996 servos have brass bushings on their secondary gear shafts, a few still have plastic bushings. I can't see any indication from the outside to tell which is which. When I get back from vacation next week I'll do a thorough teardown and inspection of the entire robot.