Our installed volt fixtures over the last couple of years has got to be over a 1000. I have replaced less than 5 sockets, a couple lenses, and some damage done by folks running over them or breaking them with mowers or gas hedge trimmers, but all are isolated incidents. All issues have been covered by sending me new parts or brand new full fixtures. Even stakes that are broken are replaced. I can't tell you they will last 10 years or more, but the track record is pretty good for now.
while they make look identical to other fixtures on the market, the other ones don't "click" like their socket does, and they don't come with 25 foot lead wire either.