Thanks for this, enjoyed reading it. I read Bernard Lietaer's 'The Mystery of Money' with great pleasure and am about to start his work 'The Future of Money' (which I assume the citation is from) (First got to finish 'Economics of Good and Evil: The Quest for Economic Meaning from Gilgamesh to Wall Street' from Tomáš Sedláček though). I also like how he (Lietaer) is a proponent of complementary (as opposed to alternative) currenies. (see: http://complementarycurrency.org/ )
BTW, there is already a cryptocurrency that has demurrage built in (or at least tries to): freicoin (not really sure if it is active anymore however)