I do understand your perspective of disliking the idea of combining database connections. In our case, we do not create a lot of data, but rather have a direct connection into the county's database for a lot of our base data layers. With more than 70 desktop users that aren't necessarily GIS savvy people... they just want to add centerlines or street lights to their map - they don't need to know which SDE connection it's from.
There are only a handful of users that will connect with edit permissions and have the ability to browse thru databases to find the data they need. So yes, primarily these folks will have a read only connection set up. The more I talk and think about it, maybe the catalog type answer I'm looking for is a combination of AGS/AGO. :confused:
Thanks for playing along!