Holly,
ArcObjects will give you a little bit more efficiency in the ability to copy data and map to new fields at the same time.
Without going into too much detail a possible geoprocessing workflow would be to use the feature class to feature class tool to set up your field mapping and copy to a new dataset, you could then use delete rows/delete features to 'clean up' the existing dataset, finally you could use copy features/copy rows to copy the data created from the feature class to feature class tool into the geodatabase.
Hope this helps.