cgsecurity.org

Forgive me if this is a dumb question, but is there a way to back up the current (likely-flawed) partition structure before >Write - ing the "new" partition structure? Or is such a thing totally not needed?

I'm just a fan of trying to provide a return to "original state" whenever possible, so just in case the recovery goes wrong, there's a "known reference point" to revert back to.

After Analyse, you can "Backup" to save the list of the partitions to a file. It's not a backup of the content of the sectors.
Keeping the testdisk.log file is also a good idea.
A true backup can be done using dd, but it's only for advanced users as you can lost data with a wrong command...