Anyone out there have a Rottweiler?

Im seriously considering getting a rottweiler. I need a dog for protection, but one that is affectionate with the family, and makes a good indoor dog. A dog that likes to go for walks, but is not a very high energy dog. Ive had German Shepherds for the last 25 years, but they have a higher energy level, and need more exercise than just one or two long walks a day. My Shepherd that I have now, is getting old, and I dont know how much longer I will have him. I have a nice size yard, but our community does not allow our yards to be fenced in, so I can tie my dog outside when he has to go or wants out for a little while. My house is fairly large, so he has lots of room inside, but I need a dog that is intimedating. We've had break ins in our neighborhood, and Im home alone with my daughter many nights. Would this be a good breed?