There are various phrases you hear used for certain breeds of dog. "Serious guard dog" "a lot of dog" "not for the inexperienced dog owner" etc. Dogs that have any combination of traits such as large size, protectiveness, aggression and/or dominance are a handful. They're also usually quite intelligent. Some dogs require a stronger owner and a much larger commitment to socialization and ongoing training, than other dogs. Otherwise you can end up with a dog that is a danger to other animals or people.
If you decide to go with a dog like that, you need to do a lot of work with it while it's still a puppy. Look for a really good breeder, that works to educate the owners of their puppies and has dogs with good temperaments. Get a good trainer lined up. Read everything you can. Be prepared to socialize your puppy to different animals, people and locations. Start training from day 1. You seem very committed to the creatures that you are responsible for, so I think you would do whatever it took to be successful.