I guess it all depends too on the breed you want the Silkies to be in with. I have Black and Blue Copper Marans, and let me tel you, the hens are EVIL HAGS to any outsiders! They are much more likely to do damage to a Silkie than my roos. I have a Blue Partridge hen that got pecked on the head HARD by an overly amourous roo. She was right around 5 months old when it happened, and I saw it happen. The next day, she looked like the Exorsist, she had brain swelling, and went wry necked. I started her on vitamins hoping against hope it might help, but no. Then the weather had a cold snap, and that seemed to bring down the swelling. She is still with me today, but everytime she gets stressed, she turns her head upsidedown, and sometimes falls over on her side. These spells only last a few seconds, then she gets up and goes about her business. She has a very vaulted skull too. She's a year old now, and broody at the moment.