Kind of hard to retreat from a bullet coming toward your back while you are retreating. Don’t think I can run that fast. Should make the home invaders feel better though.
Not really. You have to understand the rest of the NH law that is being discussed. In NH you have no obligation to retreat in your home, or its immediate surroundings, and burglars should not "feel better". RSA-627:4
II. A person is justified in using deadly force upon another person when he reasonably believes that such other person:
(a) Is about to use unlawful, deadly force against the actor or a third person;
(b) Is likely to use any unlawful force against a person present while committing or attempting to commit a burglary;
(c) Is committing or about to commit kidnapping or a forcible sex offense; or
(d) Is likely to use any unlawful force in the commission of a felony against the actor within such actor's dwelling or its curtilage.
The debate is over section III:
III. A person is not justified in using deadly force on another to defend himself or a third person from deadly force by the other if he knows that he and the third person can, with complete safety:
(a) Retreat from the encounter, except that he is not required to retreat if he is within his dwelling or its curtilage and was not the initial aggressor; or
(b) Surrender property to a person asserting a claim of right thereto; or
(c) Comply with a demand that he abstain from performing an act which he is not obliged to perform; nor is the use of deadly force justifiable when, with the purpose of causing death or serious bodily harm, the actor has provoked the use of force against himself in the same encounter.
(d) If he is a law enforcement officer or a private person assisting him at his direction and was acting pursuant to RSA 627:5, he need not retreat.
Most NH residents consider the "complete safety" part of the law ridiculous, when considered in the light of the opening section on defending ones self from deadly force. As you correctly noted, in the kind of situations addressed by the law, "complete safety" is unlikely to be part of the situation.