First not all roosters are good roosters. However, there are a lot of roosters out there. I myself, live on the prairie and have found a GOOD rooster to be very effective for day time predator protection. All of us, keep chickens in vastly different ways and set ups, and that is why you get such conflicting opinions.
My advice - look at the feed store, call your county agent, contact 4-H clubs... looking for people with extra roosters. What you want is a rooster that did not get culled because he was so nice. You want an owner with a sharp knife, as in will not keep a poor rooster.
If you get your druthers, a rooster that is close to a year old, who has been raised up in a multi-generational flock, who has been free ranging would be perfect. Don't settle for much less.
A good rooster should be the first to notice when you approach the flock. He should naturally move at least 6 feet away from you. Casually he will keep his flock behind him. He should tidbit, call to the hens, have good chicken social skills.
Seriously, cull the rooster you have now. He has had a great life, and will have one bad moment. But he is giving you multiple bad moments. No one owes a roosters opportunities to attack them.
Once you have a good rooster, you will not tolerate a rotten rooster. You become rather picky about roosters, as you know what you can have. Once you get through the cull, you are going to wonder why you waited so long to do it. Chickens should be a joy, being flogged is not.
Mrs K