Upgrade WZR-HP-G300NH to latest DD-WRT firmware

I have my WZR-HP-G30NH router running for more than 200 days without restart. As I mentioned I would upgrade the firmware to the latest one.
I have already use DD-WRT firmware. The version on my router was v24-sp2(02/24/10) std build13977. I check the router database, the latest I can use is build14896.
There are two types of files can be download from dd-wrt site.
Buffalo WZR-HP-G300NH: Special File for initial flashing buffalo_to_ddwrt_webflash-MULTI.bin
Buffalo WZR-HP-G300NH: Webflash image wzr-hp-g300nh-dd-wrt-webupgrade-MULTI.bin
The first one is used on the buffalo original firmware. Which can replace the buffalo firmware to ddwrt firmware.
The second one is to upgrade router which use ddwrt firmware already. It is for me.

I download the wzr-hp-g300nh-dd-wrt-webupgrade-MULTI.bin file.
I use the wired connection to do the upgrade. It took me about 5 minutes to write the firmware to router. Then restart.
I reset the all settings based on my records.
For wireless security. I do the following settings.
WPA2 Personal
I use 20 letters long keys.
Use MAC address filter. Only allow the certain wireless devices connection.
Let me see how stable it is. Maybe 300 days.