@vilas, it is not helping to cite an accident where the crew in question deviated from any known SOP. That does not prove anything except that some pilots should not be on board an airplane.
However, having experienced several sets of SOPs over the years i do not agree that the OEM knows best. In fact, he cannot know in which environment with which kind of training system and with what kind of average experience level the airplane is operated. Therefore he has to propose a set of SOPs that covers all possible kind of environments, training schemes and experience leves. Which invariably comes down to cater for the lowest possible standard. Which especially in the case of the current set of airbus SOPs shows very much.
We switched to those SOPs about a year ago, and the safety case made by external auditors does show clearly that the OEM SOPs are not safer or better, they are just a lot cheaper, which is basically due to the outrageous fees airbus charges for documentation implementation if one uses the airbus flysmart apps. We used a silent cockpit approach, same as our biggest local competitor (lufthansa) with no checklist at all as long as the aircraft was in motion and no FMA callouts. And it worked exceptionally well. Well, being in business longer than airbus surely helps knowing how to operate aircraft.
On the boeing it was even more obvious that even the OEM can see some extremely different SOPs to fly an aircraft that has been in service since the 1960s. The change to the "new" set of 737 SOPs around the 2008/2009 timefrage was drastic indeed, but both worked quite fine.