Kristov Atlas did a thorough review of DarkSend at the end of 2014. He found some minor issues on attack vectors and they were corrected. DarkSend has matured even better since then, and it doesn't take that long to mix. Well, at least not for the amounts I have available to me. It does depend on how many rounds and surprisingly the smaller denominations seem to take the longest.
How come this "thorough review" was never published for the community to see? Was it too embarrassing for DASH?
Why does the DASH community keep ignoring requests for a reasonable bounties to be created so that qualified people might try to test its privacy?
If the DASH claims of quality code are legitimate, you have nothing to fear and a bounty could improve credibility. If a flaw is found, it would be better to identify and fix it now until waiting until more people actually start using DASH.