Marc Nakleh - check out the MapMerger ArcMap extension developed by ESEA. They handle point, line, and polygon conflation, even at geometries of different scale - no common attribute values required. Also, the MapMerger platform supports a "change detection" capability that will satisfy your comparison requirement. The MapMerger change detection functionality will compare changes and differences among multiple datasets, and list the changes in an attributes table, and display the changes graphically on the map. Additionally, they offer a Synchronization tool that can be used to reconcile attribute and geometry differences among multiple datasets.
A set of geoprocessing Conflation tools (Editing toolbox - Conflation toolset) were released with ArcGIS Desktop 10.2.1:
They are using feature matcing techniques to find corresponding lines for spatial adjustment and attribute transfer. Common attributes are optional.
Another feature matching based tool, Detect Feature Changes (Date Management toolbox - Date Comparison toolset), was also releasd, which identifies spatial and attribute differences between two line feature classes.
http://resources.arcgis.com/en/help/main/10.2/#/Detect_Feature_Changes/001700000190000000/
Check them out!