Does anyone have any experience with the LinkSys WRT400N router and installing 3rd party firmware on it? Is there a more stable choice between DD-WRT and Tomato? Any benefits one way or the other? Any reason I shouldn't use either, or a suggestion for a different firmware?
I have mainly used DD-WRT and I have to say it is a very good firmware, it allows you to use many advanced (hidden) features within your router.
I would recommend installing it as I would consider it to be better than the stock linksys firmware.
Installation of DD-WRT is very straight forward and DD-WRT provide a lot of documentation to aid this.
The first step is to go to the router database and enter in your model "WRT400N" a listing for your router will come up and you will be able to download all necessary files.
You can also look at further documentation about your router from the DD-WRT Wiki
As of writing the latest version of DD-WRT is build 14896, don't use the version found from the wiki.
Update July 2014: Check here for the latest WRT400N build.