I have had items come up missing with USPS that had tracking and ins. Put in tickets and ended up never getting the item returned and only refund of shipping/ins.
If its anything I'm scared to lose I send Fedex or UPS. I think issues are geographical based lots of times. Meaning my local USPS are not on the ball where my Fedex or UPS are. From my location its almost always cheaper to send through Fedex or UPS with quicker guaranteed delivery dates.