As much as I feel I am doing the dirty on bmi by defending the EC vs DC, it should also be remembered that it is actually quite easy to earn Avios, especially if you are UK based. For a start as a Silver or Gold you earn a 100% mileage bonus on BA/AA/IB which compares to only 25% or 35% on bmi. You also have the Tesco avenue and various other ways to earn good miles. Certainly I've earned far more miles with EC than I would have done with DC for the same activity since I moved over.
Availability is another issue but a bit of flexibility goes a long way here.