Are you using ReSharper? It seems like ReSharper doesn’t obey the EditorBrowsable attribute.
If I turn off ReSharper, I don’t see my property. If I turn ReSharper on, it does show.
In ReSharper Options, go to Environment | IntelliSense | Completion Appearance and check “Filter members by [EditorBrowsable] attribute”.
You still have to reference the assembly though, it doesn’t work within a solution if you reference your usercontrol’s project.