If your main reason for a rooster is for him to be a protector then I'd skip it. Roosters cannot physically protect hens from attack by predators, at best they may act as an early warning system to allow hens to hide, they often loose their own lives doing so. And some roosters will beat the hens back to the barn if danger threatens! Many roosters are also a big pain in the backside to have around once the hormones hit in terms of challenging and attacking you. Yes, some are decent, but many are not! It's also common, especially in small flocks, for the rooster to have a hen or two that are his favorites and those can really get run ragged by to much rooster attention. As far as whether or not your neighbors would be upset by the crowing? I guess you'd have to ask them. Are the chickens free ranging onto the nieghbor's property or is there a fence?
I guess my advice is to really think it over before you get a rooster as far as the crowing, dealing with rooster attitude etc and that you only have 6 hens. I have a rooster with my current flock, when he is gone I'm going back to hens only.