Dashs/Darkcoins developer even said it himself: We ask that everyone stop using Darksend for the time being until we’re able to push out a fix to an issue Aswan found. This issue comes from the way fees are paid in Darksend with the combination of the way the client tries to denominate the same amount each round. The result is the possibility to trace a transaction through Darksend. To fix this issue, we will add a mixing stage to Darksend that only mixes fee’s and we’ll have the client mix random amounts each session.

So, the anonymity was broken(Even as you say, it is sub-par to other anon-schemes, (RS/ZC).

https://dashtalk.org/threads/darksend-security-bulletin.2963/