I believe Rich meant Tim Landwehr being he coauthored the book with Dave.
Being I have not read Tim Holschlag's book I cannot compare the two. I can say that this book's main focus is on methods, tactics, techniques, and fly types for fishing the three columns of water (surface, middle, and lower) under different conditions and seasons. It also spends some time discussing where to find the fish in different situations. The book has a mid-western feel to it. There are contributions by Luke Kavajecz, Nate Sipple, Kyle Zempel, Bart Landwehr, Tom Anderson, KIp Vieth, and Captain Austin Adduci. It also includes good interviews with Chuck Kraft, Lefty Kreh, Larry Dahlberg, and Mike Schultz,