Rotum,
as with everything these departures from normal start somewhere.
Pity GA, it is a requirement these days by the FOI of the day to alter the manufacurers recommended procedures. You have to comply, otherwise you dont get a tick in the box, even if you dont agree with their "opinion".
Will they put their name to it???..not likely!!...if there is an incident you just know they will say "We accepted this change...we didnt approve it" part of the CASA "All care and no responsibility" approach. Why GA is required to rewrite the flight manual is beyond me.