Flying across certainly holds a number of risks, but so does moving them by shipping container.
A few years back we were having problems with ready made garments ( on hangers ) arriving in a heap on the floor of the container. Not good news when the customer brand is a major household name.
Containers were fitted with instruments to measure the dynamic load forces inside the box while at sea. Imagine our supprise to find that at certain postions on the vessel the cargo could regularly pull 4 G's in a bad storm.
The organisers of Europe's most popular warbird show had access to a small but dedicated band of warbird enthusiasts in my old shipping company ( we were 3rd largest in the world). Support went all the way up to two main board directors. This meant that the upmost care was taken of each and every "star" for that years show, at every stage of the shipment. And much of the work was done at cost and sometimes for no charge.
As a matter of trust, those of us within the carrier that knew what was coming across never told anyone what the suprise was going to be.
Our company ceased to be 18 months ago after we were absorbed by a much larger rival. With it went the UK warbird movements access to a unique knowledge base in safe warbird carriage by sea and delivery by road at prices that weren't based on commercial gain for the carrier.
These days it's going to be done on a purely commercial basis. Any cargo above a certain value can be freighted outside the normal cargo rates on an ad valorum basis ( think 2 percent of the value of the cargo and ask yourself just how much is that TF-51 worth .....

) plus "special" handling fees, trucking etc etc.
When you look at who is planning these air moves, I'm sure that they have done a full risk assessment of the mission and godspeed them on their way.
These are just some personal thoughts on the logistics of these movements, when viewed from the nautical delivery angle.