I have a Blk JG. He's huge and beautiful. I saw his mating style today. He seems really heavy for his girls: sister who is no where near his size, bo's and delawares. Is it possible for him to actually hurt them with his weight?
IMO, the hens body and their natural squat is designed to take the weight of a roo.
I've seen no ill effects to my hens from my rowdy boys. The worst that has happened is a few lost neck feathers, but I'm seeing less and less of those now that the boys have refined their mating skills.