Hi Arie,your Buff Dutch cross onto Buff Leghorn are interesting.I like the length of leg and I think the heads look good,especially for their age.I think the white earlobes will be extra good.The comb texture looks good also.Since the Dutch were dark in shade I think that will be a plus for many years and the improved vigor and egg production should be noticed. Since you have a good number I would not use those with white in the tails.I would keep some of your pure Buff Leghorns going too help keep your Leghorn shape and feathering.By feathering,I mean the cushion and saddles.This will fill in the back in front of the tail and prevent the abrupt brake at the juncture of the back and tail.The Dutch cross appear high in the shoulder and that is a game trait,something to watch but also something that may correct itself with additional Buff Leghorn blood. If possible select against short legs and long wings,they belong on Chabo (Jap bantams) and Seramas.