As far as Dark is concerned there method is severely flawed. I have to look deeper into ring signatures to get a greater understanding. Though from what i understand that method creates data bloat that will eventually yield the coin nonviable for typical daily use.
I will continue to watch the progress of the development of these coins and others that may try to step into their shadows. In the meantime if you are wanting some level of anonymity I would suggest looking into running your wallet client through proxies and Tor. If I am not mistaken this can be done with any coin's wallet and should give you some added level of privacy. https://en.bitcoin.it/wiki/Tor
If anybody actually has any experience with my above statement please let me know as this is probably one of the more valuable/viable and over looked options out there today
https://bitcointalksearch.org/topic/annvoot-x11-vootcoin-anonymous-wallet-and-darkmarket-no-ipo-630628