Maybe this is a dumb question, but I've been wondering... what's the average lifespan of a typical camera lens? L versus non-L? Do the motors ever wear out and need replacement? What about IS lenses? Do they need more maintenence in the long run versus non-IS lenses?
With the cost of those L lenses, I would hope they'd last for a long long time. But when I'm using my 100-400mm and the IS kicks in, I wonder how long those motors can keep ticking.