Hi everyone.
Please try it, Link one group (could be a simple cube) in a new blender file, it will linke as Dupli-Group (instancing). After try to Append the same object (now appending the object not the group), the append will behave like a link no as normal Append (here is the error, I think).
If I make it local, the two objects become local no matter what I do, I think its a misbehavior, somebody could tell me?