Silkies in general are known to be a weak breed with common health problems, which has been my experience as well. But that does not mean I am saying all chickens with silkied feathering are like that. I know Silkies cannot fly well because of their feathers, how about the silkied Cochins?
I am late to this thread, but your Silkied Cochin Bantams are absolutely adorable! Do they have the same weaknesses as Silkies due to their plumage, or are they more resilient?