I prefer this article http://semiaccurate.com/2014/01/06/linksys-wrt1900ac-spritua... since it give some hints about why this thing costs $300 — if it has an Avoton Atom and 4GB of RAM it's more of a home server being sold as a router.

I have been pretty disappointed by the hackability of routers since they usually come with hardly enough RAM and flash to even perform basic duties, so even though alternate firmwares exist you probably have to strip them down to almost no features which negates the point. This router should be one of the few exceptions, being designed with extra hardware resources that can be used by hackers.