Going through a large contact merge process just now, and have a few enhancement suggestions for Merge Contacts:
1. In the Merge Contacts dialog have a “Select All” fields checkbox for each contact record that would select all the fields in that record to retain, and de-select the matching fields in all the other contact records. Would make it easier to select the fields from a “primary” contact record.
2. In the Merge Contacts dialog highlight (different text color / background?) any matching contact fields that have different text from the selected contact field. This would help to indicate if two contact records have the same value or different values in a contact field e.g. Contact1-Org:Example.com Contact2-Org:Example.com are the same so only need to retain one field, Contact1-Org:Example.com Contact2-Org:Example.org are different and if Contact2-Org was not selected to be retained the field should be highlighted differently from a retained field (to indicate potential data loss).
3. Have the option to add a Merge Contacts button in Toolbar. Currently the Merge Contacts action is towards the end of the long right-click menu.