Re: As I only live a few miles from The Hill...
The larger security issue is the availability of sensitive stuff like KMZ files plotting fibre routes accurately, which customers would insist on, even though it made their services less secure/reliable.
And knowing the exact route doesn't help the customer much, as the first time there is an outage or re-grooming, the path between major nodes changes. There is some benefit to knowing the routes of the 'last-mile' fibres, but unless you have explicitly decided to forego the benefits of automatic re-routing in case of failure, having a KMZ file of the path your data happens to be going down now is of little to no use, unless it is printed out on soft, absorbent paper.
Switching of paths on an optical network is routine, and done before protocols like BGP have put their shoes on. It is also often more hassle than it is worth to switch paths back after a fault has been cleared, unless you have mucked up your capacity planning and need to move stuff around to ensure you have the headroom to cope with the next unplanned outage. Some customers notice switching events by noticing the packet loss events and are somewhat insistent on getting as close as possible to zero packet loss, so elective switching is frowned upon.
Anyone who believes the fairy story that buying capacity from two different providers ensures your traffic goes down different paths is living in la-la-land. It is not unusual for both providers to buy capacity form the same third party, and so on (it is turtles all the way down). Buy from a single supplier, and press them hard to assure that their service is sufficiently resilient; or buy dark fibre on a known path, without switching, and light it up yourself. You are then responsible for your own resilience. Good luck.