Yeah I loved this series. Highly recommend it as you did.
I also loved their Sons of Valor books as Chunk is a cool character.
But I haven't delved into The Shepherds series yet as it seems to be too religious in my reading some of the reviews.
@Shane what's your take on Shepherds?
Other series that I loved and finished in this genre include:
Gray Man by Mark Greaney - 12 books
John Rain "world" by Barry Eisler - 22 books
Terminal List by Jack Carr - 5 books and 6th released next month
Orphan X - Greg Hurwitz - 11 books
Mitch Rapp - Vince Flynn, Kyle Mills - 21 books
Jonathan Quinn - Brett Battles - 16 books
And my favorite
Victor the Assassin by Tom Wood - 8 books