Electric fencing will be your friend. I have read instances where fox can climb up a fence. A few strands of electric fence surrounding your run is a great deterrent.
I'd get rid of these if they are attacking your sons. A mean rooster can ruin chicken keeping for life for a kid.
OK - I would say they aren't good roosters because they are attacking you and your sons. You've already been told enough times that they couldn't help because it was dark. But here's another thing to think about when depending on a rooster for flock protection. If you get a fox, coyote, dog, bobcat, raccoon, or any other such predator, if your rooster does defend them to the death, then what? You have a dead rooster who slowed down the attack, but he's just a speed bump. Once he's dead, the predator will go on to kill more of your flock. I know this through experience. While roosters can be a good alarm system, and can sometimes fight off a hawk, they cannnot be relied upon as a first and only line of defense for the flock. If and when you replace these two with another one, keep that in mind.