We are never locked out. There is no key under a rock. The phone cannot get unpaired, the remote cannot be intercepted and replayed. If we are on vacation, we can call up a friend and tell them a code so they can get in.
A 9V battery lasts about three years, then it starts flashing and beeping every time you open the door for a month before dying. If you already have the right hole in the door, it takes about 20 minutes to install.
And if you're intent on breaking in, well, the windows are made of glass. Please don't do that.
If I had a combo lock, I'd be more worried about someone with binoculars or an ultra-zoom camera watching me key my lock without covering my hand than my physical key getting lost or stolen.