The rule at my home is don't answer the first ring, if there is a second ring ask who it is and the answer "Me" is not good enough. Our neighbors have our phone number and know to call if they need anything and we do not answer the door after 9:00 PM. I can't think of any reason that someone needs to knock on my door after that time. If someone knocked and then identified themselves as LE, I still don't open the door (of course that has not happened to me in CO but did happen to me in CA, we conversed through the window until they told me what they wanted to talk about, turns out they were at the wrong house).

As to being armed at home, I figure if I am involved in a home invasion it will be at my home and I will not be invaded.