The English Orps have heavier feathering because they NEED it in that climate. Our SOP calls for less, and stiff main tails. We do not have the bone chilling dampness here, and we infused a lot of Rock during WW1, then changed from the English standard. Before they were identical.While this doesn't address survivability--but Walt did have a partial answer that I found now that I am catching up on the fast paced thread!! "Back in the day they did not have these large "beasts" they have now. When a chicken is made bigger than it should be, the legs go first and then the type. if you look at some of the monster Rocks being shown they really don't have the type that the proper sized birds have......they are just big and imposing. When I see Orps that look like like Cochins with tiny heads, I just wonder what people are thinking. Read the description of an Orp. It has to have a tail and you have to be able to see it's hocks and that is what the SOP says, but people are turning out these fluff balls and calling them Orps." Walt
The good British birds have a lot to add. They have deeper keels, and therefore more meat. They also are relatively free of shafting, in the Buffs at least. Their color is more uniform. They have great width and depth. Crossed with a good egg laying line of SOP Orps, with stiff tails, they are producing nice birds without resorting to Rock and Wyandotte mixing as so many are doing.
Come see us Walt.