@jwaltrip 

I think if you knew the device management account at least, you wouldn't have to reset everything to factory.

I learned this lesson a long time ago, with a small config.  Now, any time I change controllers or update firmware on a controller, I take a backup immediately.

Personally I think TPLink should enforce this behaviour, after any initial setup, or any firmware upgrade, or site migration...a backup file needs to be downloaded somewhere to continue.