Hi Flex,
You are right, the ATR training centre based in Toulouse published a kind of SOP manual, very well illustrated and user friendly for the different types of ATRs. I remember, I read it about a year ago and have to say that regarding flight technique is quite complete and useful, however at the very end of the book it states something like the manual was made by the ATR Training Centre and it does not intend to replace or supersede any official publication. Therefore, I assume that Flight Crew Operating Manual is the official one and probably was created by other people. I still have that doubt wheter the ATR Training Centre is a separate organization and they recommend the ATR's operation rather than officially dictate the operational procedures. In fact, some of the actions read in the FCOM´s normal procedures section differs from the mentioned flight technique.
The major drawback of the FCOM is the summarization of the procedures and some parts you might find incomplete, perhaps missing as opposed to the well described FCTM.