Shipping with Insurance / No insurance

I've always shipped bodies/lenses with insurance thru UPS or Fedex.
I even add signature delivery for safety.

It gets really expensive shipping via this method.
So, my question is, has anyone shipped a lens/body via UPS/Fedex ground with signature and had an issue with damage/being lost?

I almost always ship via USPS Priority Mail fully insured with delivery confirmation or signature required.

Insurance is always assumed when I sell stuff. I would expect the same when I buy stuff, but unfortunately that's not always the case.

Signature required is a good idea when selling stuff, this way the people can't come back to you and say they never got it. I have all of my gear insured, and my insurance agent told me not to bother insuring stuff when shipping it, as my policy is better than UPS's.