I personally wouldn't get a silkie if I already had an established flock that are almost matured. I know from experience how bad a silkie can get beat up if thrown into a flock that are much bigger and not as friendly. Just watch out! Hatchery silkies are a little tougher because their crests don't interfere with their vision.
I definitely agree there is no easy breed to add into an already established flock although some breeds are stronger therefore are higher up into the pecking order. It may not be specific breeder its more of the personality. Some silkies are rough and are very strong. I know some barred rocks that are wimps also! Just keep an eye on the new silkie you get and you should be fine.
My silkies are kept seperate from the big girls,they would terrorize them and it would be horrible for the silkies.They can all see one another and they are in the same coop but all are seperated by fencing.
I am contemplating adding Silkies to my chick order. I'm going to order with MyPetChicken.com and they have several colors of Silkie available. Maybe check them out for your chicks? But I'm really wanting egg layers... and it doesn't mention how they lay or how big their eggs are. But they are beautiful looking!