UPDATE: I've worked out an agreement with Moog Music regarding the installation of the ESPE01 module, and its impact on active warranties.
The agreement is that I will provide module installatin clients with written documentation regarding the installation of the module, complete with date of installation, my name, ect.
As long as clients who have the work done by me, or someone else who has this agreement in place with Moog Music, includes the documentation with their RMA when returning a theremin for service to Moog Music, the warranty will remain active.
In Moog Music's words, their theremins are the only instrument in which they encourage enhancements by their theremins' owners.
So, from now on, anyone who has a module installed by me will also get a written document concerning my work to install the module. I may also make a miniature document that can be affixed inside the instrument as well, in case the big document becomes lost.