Now I'm back with lower dps (250 or so with 40 pickup radius, or around 285 w a bit less pur). I have been doing vault of the assassin(vota) runs, and did it on MP3 for a while (clearing in about 5-6 mins or so).
today, back to MP1, I can clear VotA in just over 3 minutes. I get at least 1 DE per run. I'd say an average of about 1.5. I've gotten 0 once in all my runs today. I do often get 2, and very rarely more (4 was the most).
Also got some nice legendaries and the usual brimstones.
I am doing it w legacy nats but I think a non-legacy dh should be able to do the run in around 3:30 to 4 minutes.
TLDR: if you are doing Cota and are averaging 3 minutes per run (for a 30%(?) chance of getting a DE), you might want to consider doing vota runs for an almost sure DE, maybe even more (you'll also get more xp if you are still levelling up)