Drew,
It is my guess (and it is just that, a guess) that you might get 1-2 of the dark type out of a spawn. With what Hans has shared with his knowledge of the genetics of the strain (silver pigeon x Blue diamond x Marlboro red), I think it is highly unlikely that the DA's will breed 100% true.
Perhaps the Dark ones you are seeing are either missing the BD gene, or something to do with the coloration that in inherited from the MR. At any rate it will be extremely interesting to compare your results breeding two dark angels to my results breeding a Dark Angel to a Blue diamond. I am also getting a jumbo Blue Ss from Hans this saturday, of which I plan on breeding to the double dark angel I have. Comparing all three spawns should give a pretty good idea of the basic genetic makeup of the Dark Angel.
I asked about the coloration of your fry as mine are nearing two weeks and I am suprised to see the amount of red in them, but I expect this will fade just as you have witnessed with your group.
Rick