The Netgear Nighthawk R7500 X4 has a design point that supposedly lowers latency specifically with gaming in mind. It also has a dynamic QOS that functions by looking at both devices and applications. So for example an X360 playing a movie will get lower priority then the X360 playing a game.
Regarding your open NAT not sure what you are asking. Setting up the router with your consoles will not require any manual setup short of the basic router setup. Connecting to your ISP, setting wifi SSID and security to what you want etc. The routers are otherwise ready to go.
The Dynamic QOS will be rolled out to the other Nighthawk routers in Q1 2015. Not certain it will work exactly the same but my guess is it will be close.
Again I want to make the point that in regards to gaming Netgear believes the R7500 is the best router to get.
Bob Silver
Netgear Consultant