Just updated mine. Surprisingly my backup settings worked this time when restored.
Any idea how this firmware compares to RT-N66U_9.1.0.3_125 ? I assume RT-N66U_9.1.0.3_125 is newer since it's 9.1, or maybe not.
Just a note, you have to be very careful when restoring old settings when you move to the next firmware version. Some old settings may not apply to the new firmware, new settings may be added, old ones removed, and how the setting values are interpreted by the firmware may change. So you may end up with subtle (or not-so-subtle problems). I would recommend moving your settings forward manually.
Of course, you may have no problems as a result of this, but just wanted to point out that there is risk involved.