I allow barking.
I EXPECT protection from my dogs. I know for a fact that Weda, and every pit bull that I have had (many), would die protecting my family, and that's how I want it. My dogs have always known that my property is my property.
That's my personal opinion and preference, I know that many will disagree.
The first night that we brought the new baby home, we did an introduction with Weda, she immediately took to her and understood her role. That night, one of my wife's family members stopped by to drop something off. She'd never been to our house. She came in, but was in a rush. Weda was sniffing her, and fine, but she was rushing around too much in the house, and rushed over to the baby, the moment she leaned over the baby, Weda let out a big boom bark, and came over next to the baby. I told her OK (not the consoling ok, I have my own OK command), and she understood that the "guest's" behavior was acceptable, and she went into a sit and relaxed.
Perfectly acceptable behavior IMO, and she was actually treated after the guest left.
In the past, I had another dog ("Cinnamon"), who was a 45lb muscle bitch, and she took down a 80lb-ish mastiff-horse looking thing that was going towards my oldest daughter when she was in a walker at 8months old. I was running towards the dog with a stick, but Cinnamon rammed it and took it down and held it 'in place' until I got there.
I've had some good dogs . . . ahhh . . . the memories.