Darkcoin is in my opinion more dangerous than mere Bitcoin mixing because masternodes can very easily be DDOSed (masternodes' IP are broadcasted in plain text). This means that any sufficiently motivated organisations ("SMO", read: a lot of money, like many government agencies throughout the world, the NSA being far from the only one) can just buy a lot of DRK, set up a lot of masternodes and, using their massive computing power, execute a DDOS on the masternodes they don't own until the masternode's owners give up - this being done over time, to not make the DRK user suspicious, which is all that easy since masternoding naturally encourages killing the competition, since less competition means more money for you, much like the poolmining economy. Once all the other masternodes have given up, the remaining ones are the SMO's masternodes and then the fun begins. Another possibility is to simply issue a subpoena duces tecum (civilist countries have something similar) tied to legal interdiction to ever mention the subpoena (FISA warrant, anyone?). From this point on, honeypotting is just the way to go to gather enough data to convict as much users as possible later on.
