'But Embassy Chess is only yet another Capablanca variant.'
And Embassy Chess is available to play elsewhere - I am playing it at Brainking. I think chessvariants.org would be better served by including variants not easily playable elsewhere - for example, the Gustav III's chess suggested by Mats Winther looks very interesting.
(Same goes for Knightmate - I am currently playing that on Brainking as well, and would much prefer the chance when playing here to get to try out some new variant not available on other sites.)
I would like to sign up for this tournament (even if it does include Embassy Chess and Knightmate chess as two of the games).