Thank you Penko. You have guessed correctly.
I think I have been misunderstood. To my knowledge all modern aircraft are flight tested to ensure that they can be safely operated by appropriately trained average pilots, not super heros. Manufacturers will also flight test various configurations and publish the results. Not all configurations will be approved for normal landings. At the same time performance data will be produced for configuration. As line pilots we fly using this data with additional margins added to the basic numbers. Some margins are added by legislation, others by companies.
Which configuration should you use? Others have already answered that question.
But my point is that having certain manufacturer approved configurations denied because of company policy does not make sense. Should incident and QAR data imply that certain configurations result in more 'events' then that is something that should be taken up with the training dept. and/or manufacturer because this is something that should not happen.