I have never tried Bluebirds so I am no help with those; but I do shave exclusively with feathers and I have plenty of both - black and yellow ones. As others already mentioned, they are both excellent blades and once they are in a razor I woud not be able to tell any difference whatsoever. I get great shaves with either one of them. I recall there was actually a thread that some people like the black ones more than the new yellows because the coating makes the blade less sharp comparing to the uncoated ones. Again, to me it makes no difference at all so I would not bother if I was you. Of course, it is your call 
