I put in a blue roo and a buff hen and it said 1/2 your chicks will be blue and the other half BLACK..... hmmm
The Kip Calculator is an excellent tool but has to be generalised. The restrictors necessary to completely remove black from buff bids affect the black or blue to give results similar to those of the birds in the pic.
Krys is right. Many folks use this cross to work on "lemon blues" ...a very beautiful variety. But, I believe you would also need brown red to complete the cocktail.