I've always kept all chooks together, even when the flock was up to over 100 birds... At least half were cockerels, but never a fight. I think it's important to raise them together so, like Ridgerunner says, the potential for violence goes way down. Makes knowing the parents difficult though so I would just temporarily separate the chosen breeders. In my experience, roosters and hens generally like having a choice of partners, and a solo rooster is a more tense bird.
I think hens should always be given a choice of rooster, otherwise you might be forcing the breeding of a male they know is unworthy, just because there's no other options. Obviously not an option with pure-breeders, but I do mixes and am working on my own strain. I've tried in vain for years to get my best hens to view what I thought of as the best roosters in a romantic light, but they'd choose boys I didn't think so good, and produce great offspring. When I managed to breed them with what I thought were the better boys, the truth came out... Crap genes. They just KNEW. They'd flock around the dominant boys when it was time for food, mate with them when an egg was in the way, but when fertile they'd lag behind, and when he went around a corner or out of sight, they'd actually run, to slip off into the bushes to mate with the rooster of their choice. They knew when to mate to avoid 'pregnancy' and when to mate to get 'pregnant' --- bizarre!
I do believe in the lovechild theory, because it seems to be true. A rooster and hen who choose eachother above all others seem to breed the best offspring of all.