Having been involved in certification takeoff and landing flight test in years gone past, and certification generally, my attitude is that anything published and claiming to be unfactored effectively means, for the line pilot, unable to be achieved. My comment ought to be viewed in terms of the data becoming a limiting boundary condition ... hence my preference to get students to apply the normal factors as part of their assessment and decision-making processes when it comes to weighing up to which runway does one divert ...
If my position is a little conservative, so be it.
I think that it would be very hard to argue the toss at the Inquiry after an overrun on the basis that the book said the distance available was the unfactored distance required.
Different matter, of course, if the pilot is faced with an emergency requiring an urgent landing and there is no alternative runway available and that runway was the reasonably assessed best option.