Hi Thomas, I've reviewed the proposed change.
`org-scan-tags' already does many things beyond its name, because a "tag" here is really a "match", which can include properties -- see `org-make-tags-matcher' for how the "tags match" is built from properties). This is handy for tags view and `org-sparse-tree'. In agenda, we don't need to display the properties that are part of the tag match, as they are part of the agenda headline already. I don't think we should let the user add properties to the agenda lines this way, as (1) it would make the name `org-scan-tags' even more confusing and (2) it would probably slow down agenda creating a lot -- `org-scan-tags' is the bottleneck for speed here. Also, the whole purpose of `org-agenda-columns' is precisely to see properties in agenda, so I'd rather let the user interactively decide if he wants to take the extra mile (and time) or not. 'hope this sounds reasonable enough. And thanks anyway for this! -- Bastien