On the configuration for an Import Job Process > Constituent Update Rules > Address/Phone/Email Updates, there is an option for if a matching contact record is found, to "Update matched <record> (except start date and info source)". It would be great if the Information Source Comments would be included in that exception, as it is really just an extension for the Information Source, and we don't want to overwrite the original comments but might want to update other fields on the record (primary flag, end date, Do not use, etc.)