The police in my area suggestd the Beware of Dogs sign to me. Because I know if a stranger comes in the house or yard without me, chances of my dog Bear biting them is quite high. Not 100% chance but high. He has a record already of biting a couple people who came in without knocking before, no serious injuries, skin only broken once. Never my family or house members, mostly friends who felt like it would be okay to just come on in even though Bear is going crazy in the window- right next to the Beware of Dog sign!
They said it alleviates some of the responsibility from me, because the sign clearly warns to BEWARE of the dog. He MAY or MAY NOT bite a stranger. Either way they need to BEWARE. He is with me for protection. Bear loves kids, my family, cats and small animals, but not strangers approaching the home turf. Unless I or family introduces him, he doesnt like strangers. Fine at the vet or groomer etc. But not at home.
Though your dog doesnt have history, so like others said, depends on your area and situation.