This update is quite interesting actually
is the updater-script.
The only "main" check here is that you're not downgrading the version of the firmware, via a ro.build.date.utc, and that the device being flashed is a C6806.
Asides from that, it's a regular full install to the device.
The only "patch" file is recovery-from-boot.p, which will only update the recovery if it needs done. This seems to be designed to prevent a downgrade of recovery (you can't downgrade it if the zip always tries a binary patch on it).