New R6400 and DD-WRT - beginner questions

Hi everyone,

I just purchased my first wireless AC router, and it's a Netgear R6400. I'm interested in the additional customizability afforded by DD-WRT. However, I have a few specific questions about changing firmware. Specifically, my router is currently running the stock version (V1.0.1.6_1.0.4) that was installed when I opened the box. I now have the option to update to the new Netgear firmware V1.0.1.12 (http://kb.netgear.com/app/answers/detail/a_id/30765?cid=wmt_netgear_organic) or the newest Kong R6400 firmware (http://www.myopenrouter.com/download/dd-wrt-netgear-r6400-kong-mod-updat...). Both of these files are CHK files.

Since this would be the first time I've ever put non-stock firmware on my router, I'm wondering if using the Kong Mod will void my warranty, or whether I risk messing up my router. Also, if I want to go back to the stock firmware (either V1.0.1.6 or V1.0.1.12), how would I go about doing that? Thanks.  My primary reason for testing out DD-WRT is to use the DFS channels since somehow the other 5 GHz channels around me are kind of clogged. Any advice there would be helpful too. Thanks!

B.