My bro has a Dark Horse clone as well as a Mutation V3. I've puffed on both of them, quite a bit (even gave him my cold hehe). Out of those two, we both agree that the Mutation V3 takes the prize. I think the spiral airflow actually makes a difference. Keep in mind, he is pretty good at building coils. If I was gonna buy an RDA right now, however, it would not be either of those. I would take the chance on the Freakshow, even having never hit one. That thing is seriously calling my name. Love the idea of hex heads (allen screws) on the posts, as well as the placement of the airflow.
Honestly though, I can't think of ONE bad thing to say about his Mutation V3 and he seems REALLY happy with it.