First, love this plugin! Great work!
There are times when I need to import and all I have are email addresses. When the import is complete, any records that were created contain just an email address. However, there are times that a record with the same email address exists, but it is inactive. When this happens, I will typically export the import results, filter the rows that include "new contact", copy the email address, and search for it in Advanced Find. That will list the new record with only an email address and the old inactive record with all the info. I then select the inactive record, activate it, then select both records and merge the newly created on into the old one I just activated.
If there was an option to include inactive records in the search and then activate that record and include it in the list, that would be great. The only snag I can think of is if there are multiple inactive records.