Recently sold a '64 Re-edition Carrera on the forums that was 'lost' by the USPS in transit.
(Model CS3110 - silver dial - serial 07909)
Fortunately, the package was insured and the value was recovered (after a two month process).
I have shipped hundreds of insured USPS express mail packages with no issues. Usually, I physically drop the package off at my post office.
In this case I requested 'carrier pickup' as it was a Saturday and I handed the package to my mail carrier and that was the last time it was seen.