"A chaum token bank may be blinded but is still a great big single central point of failure and control...they can still selectively deny access." That is not

"A chaum token bank may be blinded but is still a great big single central point of failure and control...they can still selectively deny access." That is not really true when there is an offline transaction protocol; the bank can only deny access initially (e.g. the bank can refuse to let you open an account), but once you are in the system you can spend money or be paid without the bank's permission. It is also possible to create threshold systems where there is no single bank, so that there is no single point of failure. "Chaum's system provides some properties "perfectly" but they aren't the properties such a system needed to have in order to exist, much less be successful." I think protection against double spending is a pretty fundamental property for a digital cash system to be successful. People would not use Bitcoin if they did not believe that it protects them from double spending. My only real point in all of this is that Bitcoin does not provide that protection according to the standard used by cryptographers; in practice, nobody has pulled off a double spending attack yet, but everyone knows how to do it and it is not impractical by any stretch of the imagination.