Some of the information in the book In The Gravest Extreme is outdated – some laws have changed, and when this book was written Glocks were not around.
That being said, combat mindset does not change over time – If you took a medieval knight and transported him to this era, he would simply begin training in firearms and trade in his plate for Kevlar.
Ayoob uses common sense scenarios to explain concepts- he clearly articulates why avoidance is better than confrontation, and shows why just having a gun is not enough – you must know how (and WHEN) to use it.
This is a good book, Ayoob is a talented and practiced author – you will learn something from this title.
I use information from this book as well as the Ayoob Files when discussing combatives and proper mindset in the various firearm classes I teach. I believe that to be a good instructor of any discipline, but especially a self defense related field you need to constantly learn, read, and practice.
You cannot learn a combat mindset in a vacuum, it is not natural to run toward gunfire, you need exposure to the concept from people who have done it.