Add the ability when enabling attachments on feature classes, I have the option to store just a link to files in the attachments table. I would much rather store Photos, Documents, and other files related to a feature in a place on a shared drive so anyone and any application can easily get to them without ArcGIS. I don't want to store blobs for photos and documents in our database. Storing blobs in SDE means any other application we write that needs to see those attachments will have to tack on some ArcObjects code to pull out the file.
This would be similar to the difference between managed and unmanaged raster catalogs.