Your wife is a very intelligent and knowledgeable woman!  

I like the fact that shooting a shotgun for me consists of shooting out eight .36" balls ("000 buck")  in the general direction of the 'invader'. every time you pump and pull the trigger.  

Based on my own personal experience, there is nothing louder or more attention-getting than racking a 12-gauge pump shotgun at 3:00 o'clock in the morning near someone who is next to a stolen car!  The noise of firing it is also absolutely terrifying!

The 'chambered'/'un-chambered argument' is more dependent on how much you trust your safety and how imminent actual combat is.  

The guy who took out Osama Bin Laden versus your wife's pistol, wherever she keeps it.