As one source wrote to a friend: "Don't let the prototypes fool you.'
Smith is being quiet as to exactly what the issue is, but my understanding is that the goal of the DBE framed M&P is to meet or exceed every military spec and environment demand in the regular production gun and the variation will NOT be made available until that goal is reached.
(No, I'm not sure exactly what that means in terms of a difference between the black and DEB.)
From what I've heard, the goal has now been met and it's a matter of scheduling and feeding production schedules in a VERY busy plant.