ArcGIS Diagrammer does not have the option to create a parcel fabric conceptually and modify the properties accordingly. The ability to export and import xmls would be great for ArcGIS Diagrammer.
Also, the Geodatabase Diagrammer for 10 does not create a parcel fabric Visio model at all.
Any of the solutions above would be very interesting for the following reasons:
1. To view & understand the underlying parcel fabric model and hidden relationships
3. To model proposed / production datasets for review or general records