Jim, here's a link to a discussion about it"
http://www.strategypage.com/military.../30-76965.aspx
On Feldgrau and AHF,
The Devil's Guard has been beat to death, almost as badly as
The Forgotten Soldier! Some people have read Fall's work, which seems to indicate the number of SS was in the low hundreds, rather than thousands. Possibly only a couple of hundred. Of course, it's entirely possible that Fall misrepresented the numbers as well, since SS men fighting for France would have been tres terrible!
For myself, I love reading it. While I don't think it's entirely factual, my opinion is that it's based on fact. There are things in there that even an imaginative author with no military experience would have had trouble making up. I believe the story happened, but not quite the way it is presented in the book.