If you don't want to rescan each time, and there is no other person/process/profile that would be changing the resulting copies at Destination, then yes, you can consider Fast Backup.
When you said "In Source, I sometimes edit, sometimes delete, sometimes add new files.", do you mean you intend to do that manually (by yourself)? Or are you planning to set up a 2-way Sync (SmartSync) profile in which changes are made to both sides?
Fast Backup can't be used in a synchronization profile nor a Restore (function is disabled):
http://support.2brightsparks.com/knowledgebase/articles/215524-using-fast-backups-on-all-profile-types
However, it's possible to set up a Mirror profile type with Fast Backup, although you will need a traditional Fast Backup (not 'archival'/bit-based, etc) since archival Fast Backups have no database which acts as a memory to remember if files exist on Destination that are (no longer?) on Source during a non-Rescan run.
When you said "In Source, I sometimes edit, sometimes delete, sometimes add new files.", do you mean you intend to do that manually (by yourself)? Or are you planning to set up a 2-way Sync (SmartSync) profile in which changes are made to both sides?
Fast Backup can't be used in a synchronization profile nor a Restore (function is disabled):
http://support.2brightsparks.com/knowledgebase/articles/215524-using-fast-backups-on-all-profile-types
However, it's possible to set up a Mirror profile type with Fast Backup, although you will need a traditional Fast Backup (not 'archival'/bit-based, etc) since archival Fast Backups have no database which acts as a memory to remember if files exist on Destination that are (no longer?) on Source during a non-Rescan run.