Elliot - I got the certificate for my TR. I found it interesting, confirming much of the car's history, originality, etc. Also had a few surprises, but nothing material and I can't remember it anyway. Wish I'd kept a photo of it.
For centuries I've been a pack rat, so when I got a "classic" car, I always built up an inventory of original documents, manuals, restoration photos, magazine "reviews when new", etc.
I think having such a packet, including the Certificate, adds to the credibility of me as an owner who cares about the car, and helps show I'm not a "flipper".
Anyway, if the Certificates were available for MG TDs, I'd certainly order one for my current MG. As I'm the second owner, I've got the car's original trophy badges, event badges, manuals, tool kit, even the original Lucas and Lockheed replacement parts kits - as well as 1953 magazines with reviews.
Tom M.