Both the project management cycle (PMC) and the Project Design Document are standard instruments at Swiss Humanitarian Aid (with some differences, of course), and I guess they are standards nowadays with most major humanitarian and development agencies.
Participation in the PMC (the “A” moments) has an obvious justification, but in practice we are often confronted with the fact that people from among the beneficiaries do not understand the PMC / PDD /DRM vocabulary. So it seems good to have these interaction moments, but not necessarily a sort of formal “co-management”. Local governent officials and technicians, as well as community leaders (male and female) can typically be invited to key PMC moments.
In order to facilitate a later impact assessment, it should be good practice to identify a reference group of people (community) which will not benefit from the project, so as to compare their state to the state of the beneficiaries, later on.
As to the PDD, I found the examples very useful. They are not of PDRM projects per se (one is for recovery, the other of a particular training, which is rather like an activity of a larger project), but they do provide a good insight into how a PDD is structured.