Consider this: The Milepost is updated EVERY YEAR. The Churches book is years out of date.
The Milepost names every campground on all the routes without the prejudices and preconceived notions that the Churches often bring to their writing...to say nothing of the many many mistakes I have found in their books. Dont get me wrong they are nice people but not up to the journalistic standards of accuracy that the Milepost is.
There really is no need for two books. The Milepost is THE standard by which all others are measured...and in my opinion the Churches book just doesn't make the cut.
I used the 2016 version of the Milepost to go to Alaska this spring traveling all over the state from Skagway to well North of Fairbanks and covering almost all of Alaskas roads from the Kenai, Homer, Valdez, Seward, Denali, and the Taylor Hwy to Dawson. So I speak from some modest experience.