Hi Mike and Richard, Yes, it would be nice, but only Map and Civil users can see anything that is FDO related. Any other AutoCAD product will just ignore that content, and there is no object enabler that will allow it's usage.

No, not yet. At the moment, ArcGIS is only a 32 bit application, so it and Map 64 bit can't communicate. It does work nicely on a 32 bit system via the ArcGIS FDO provider, or even via the OGR provider for personal geodatabases. OSGEO does have a 64 bit OGR provider posted, but I haven't been able to get it working thus far.

Thought I already posted this, but here goes again: It depends on how you'll use the data - if you have multiple users of a file, or it is updated often, then an FDO connection is likely better. If you are the only user, or you need to make the data available to AutoCAD (not Map or Civil users), then importing is the best options. Some tools like MAPCLEAN are only usable on imported objects, so there is even a place for an import, clean, export process.