@Rincewind , you are correct.
Objective of the IMDRF is set-up a structure of technical documentation "filing", that ensures that you have captured all required elements and requirements from the main regulatory area's. It can require a large investment in reorganizing current dossiers, but for products that require WW submissions it is definitely to be considered.
Regarding the STED, the MDR has basically taken over the text from the former GHTF document in their Annex II, with some EU specifics. Therefore when following already the STED document, I do not see a need to reshuffle all.
And regarding an SOP on TD's, please consider establishing a good template structure, that is linked to Design Control, Risk Management, Clinical Evaluation and PMS. Thats more valuable.