I just replaced the bb in my Trek 6700 hardtail...a bike that has seen some hard use.
The bb was a low end Acera and lasted about 4000 miles before it needed replacement and was on the bike when I bought it used... the bike needed a full drive train replacement when I purchased it so that bb probably had a lot more miles on it.
The Dura Ace (and XTR) bottom brackets can be serviced / adjusted unlike Shimano's other cartridge bb's.