Harry Again. You may have good personal reasons for not trusting manufacturer's SOP's but at least you can be sure that a lot of R&D have gone into the design of their SOP's. The big manufacturer's test pilots are experts in their field and I for one am perfectly happy to accept their recommendations. I know those recommendations are based on handling facts - not some four bar and a star check captains personal hobby horse opinion.
In the airline industry local SOP's change with the wind - or when a new broom is promoted.
Have you ever seen the myriad ways that a simple engine failure/fire after take off in a 737 or 727 for example is presented as an SOP by different operators flying the identical aircraft type?
I have, and it all becomes a grand Shakespearean act of who says what and who pulls which and who confirms what.