There needs to be a better way to repair the broken workspace references in MXD's or change the existing references. The Set Data Source command in Catalog is hard to use and needs to be improved as well as resourcing multiple maps at once.
At 9.4 resourcing multiple mxds can be done through Python using the new arcpy.mapping module.
See help topics:
Professional Library > Mapping and Visualization > Using ArcMap > Automating map workflows > Map Automation Professional Library > Geoprocessing > The arcpy site package > mapping sub package.
As well as the Tech Transfer videos.
Pre 9.4: If workflow exists where new server and database are setup, however organization has multitudes of dedicated MXD's pointing to old server which organization wants to later re-direct. Testing has shown that if a valid dummy database connection is set up for the broken links the MXD will time-out and open with the option to repair data sources nearly as quickly as default behavior. Below are steps to reproduce described scenario:
1.) Create a new SDE database over the network so it can be disconnected from the mxd file that will be created in Step 4 2.) Add 3 or 4 feature classes (eg. Parcels, road centerlines, places (points)) 3.) Make a backup of this database (replicate the database) 4.) Create an mxd file using all the feature classes created in Step 2 5.) Save the mxd file locally and close out of it....default behavior 30 seconds 6.) Remove computer from network so mxd can not access the SDE database 7.) Open the mxd file to see if it will hang on the invalid SDE......5-6 minutes connections (Measure how long it takes to open the mxd) 8.) Reconnect computer to network 9.) Delete the feature classes from the database 10.) Open the mxd file when there is a legitimate SDE connection with no data contained....45 seconds