I used to have a Minivault, which is the one with the 4 buttons and a programmable code, but switched to the Nanovault. No batteries or power outages to worry about. I keep the key taped to the underside of my bed frame, back to where you would have to flip the bed upside down to find it if you didn't know it was there, but easily accessed if you know where it is.
All of our bed rooms are on the second floor, so from the moment my alarm goes of, full sprint, it would take someone roughly 7 seconds to make it to the first landing. It takes me roughly 5 seconds to go from laying in bed, to round in the chamber, covering the hallway and stairs. My fiance is about 6 seconds. Still working on her speed a little.