I too have the daydreaming problem. Its just more incentive to sleep through class. However, I have a 2000 400EX, ride very hard in gravel pits without any problems with the axle. However, I have two friends that also own the same bike and have had the axle carriers loosen a couple of times.
The moral of the story is this: if you ride hard and often, it will cost you money regardless of what your ride is. Stop worrying and get a better paying job.