Cary,
Agreed they are nearly bulletproof!
I've been using them since 2008 and never had one "fail" but they do tend to wear out gracefully, so you know it's going to give up the ghost!
That is why I keep 3 and when one shows a lot of wear and tear, I pull it, replace it, and send the other off to refurb! There is something rugged and reliable I like about them!