You may not be convinced. I am.
And just out of curiosity, how can you possibly say with any credibilty that "I think it's safe to say that the "projection" of 80% charge left after 20 years is nothing more than speculation and is just part of the marketing bumf?" This technology is new and hasn't been around long enough to judge that. I trust their projection a hell of a lot more than your negative assessment of their estimates. And as long as they are willing to back up their battery who cares?