So.... how could you custom-build something akin to say, the Netgear Nighthawk (Netgear R8000)? I'm thinking multiple 802.11ac antennae with all that new multi-user beamforming stuff that's been released lately. Is there open firmware that supports that / do the commodity Linux drivers support controlling and fine-tuning that kind of function?
Added: Interesting.... There's an x86 port of DD-WRT: