So far I ended up using acs_rels to associate one "news item" to another.
That way
1) I kept the structure as it is (many instances of news mounted under subsites and dotlrn communities)
2) The feature is parameterized, so, only chosen instances are able to replicate its news to others.
3) Plus, with acs_rels I can easily track what "news items" are replicated and then make the necessary amends in case the original item has been edit.
4) The "news items" are associated, but the fact that they are not the same any more, it offers the possibility to customize the news even further.
For example I created new templates do display "news items" accordingly to the priority and the sort order, which btw they change from one instance to another.
Thus, in the Mainsite we have the "news item" as an important one, "Breaking News", located in the first page with photo, large fonts and etc.
http://www.mda.gov.br/portal
But, the replicated "news item" is in a subsite under mainsite with no photo, smaller fonts, as a secondary item.
http://www.mda.gov.br/plano-safra
Furthermore,
I still can't picture how permissions applied to only one instance of the news pkg working for many subites would substitute the structure of different instances on different subsites and dotlrn communities.
So please, Ryan if you have time it would be great to see how that works out.