I've been running my Shimano 3n71 for 6 years now, about 6500 miles or so. I haven't even had it overhauled. Maybe I'll have that done over the holidays. I would recommend replacing the tail light wiring every year if your doing a lot of riding; it's the one part that can fail plus it's not noticeable when it does - mostly due to wire movement at the connections or coming loose at a mounting point such as inside your fender. I also use a secondary battery operated tail light in poor conditions such as fog, rain, or snow (both the dyno powered and the battery powered tail lights have built-in reflectors).