This book, published a year ago, has just come to my attention, and I have purchased a copy.
https://www.amazon.com/Operational-A...6&unfiltered=1 (if the link doesn't work, just search on Mary Hudson as author, and RAF as title.)
The author is Mary Hudson, who worked with these records for many years, and is now retired. It is 302 pages, with many examples of the actual reports, both RAF and German. The German records of course apply to the USAAF, and so much of the book will be of use to American researchers. One should note that the records sent to the NA/PRO cover operational losses and (aircraft) accidents. Records covering illness, automobile accidents, etc, have been retained by the RAF. The book also covers the various changes made to the casualty process during the war, and their current status.
I highly recommend this book to anyone involved with casualty research.
Enjoy!
Frank.