ROOTED THE UPDATE SUCCESSFULLY
Reverted to stock recovery, flashed custom recovery, flashed SuperSU.. rooted!
No problems
UPDATE: SuperSU is not working after boot. It says "Unauthorized access to a secured area has been blocked" does anyone know how to get around this??
SECOND UPDATE: After rebooting, it has reverted me to the stock recovery. This is crazy. Hopefully someone can help with this.. or post a version of 4.3 without this Knox pain in the..
THIRD UPDATE: EDIT: I fixed it!! I have root access! I was able to locate SuperSU in system/app and reinstall; load up SuperSU and enable survival mode. Now I'm freezing Knox with Titanium Backup