I think your biggest advantage with a silent dog is when you first turn out and they first find the hog. The hog doesn't know they are coming and all of a sudden there is a dog in their face. I believe some hogs that would have run if they heard a dog barking will stand there and fight at least for a few minutes if a dog surprises them.. After that if the hog breaks then yeah he knows something is after him and your odds do go down a little.
I agree that a lot of silent dogs will yip a little out of excitement right behind a hog after it breaks and then shut back up. Or mine do...
i agree with chain on this a hundred percent