Just ready your entire book over the last two weeks. Excellent!!
I have two comments. Number one: In your post for this thread you commented that running forefoot in situations involving mud is not efficient and would be best being done using a heal strike stride. You just confirmed an observation I have made over and over while running muddy trails. I am also thankful that I am not weird in switching from forefoot on harder trail surfaces to heal strike in muddy root filled trail sections. I kept feeling like I needed to pick one or the other!
Number two: In reading your book I kept wondering how can I adapt your training regiments to someone such as myself that runs exclusively in the mountains and on trails. In December I am beginning your Level 2 marathon training and am struggling with figuring out how many miles I should be running. My 18 mile long runs are usually filled with 5,000+ and 5,000- elevation gain/loss with extremely difficult footing. Would it still be appropriate for me to adhere to your mileage suggestions even though they were meant for the road?
Finally the two most important revelations I got from your book were: Training using intervals that are close to race pace and hill sprints for the injury prone runner. Absolutely good stuff in my running sphere!
Cheers,