Sadly, it appears that we can't draw any solid conclusions from this thread. Everyone seems to have their favorite parcel shipper for their own good reasons. I've had maybe 50-60 guns shipped by either USPS, UPS, or FedEx. Personally, I cringe when I'm told a gun will be shipped to me or my FFL by FedEx. The majority have been shipped by USPS and I never had any delay, damage, or tracking issues. Every long gun shipped to me by FedEx has shown signs of rough handling. Two guns were broken through the wrist, and one had the barrels poking through the box. The YouTube video of the FedEx guy tossing a Plasma TV over a 7 foot iron fence is troubling.
Admittedly, part of the problem is how the gun is packaged by the sender. I don't know why anyone in their right mind would ship a double assembled and full length. The long skinny box is much more prone to damage, and it just screams that there may be a gun inside.