FWIW I upgraded a Cisco/Linksys E4200 to an Asus RT-AC68U, the only other router that appears to go neck-to-neck with the Nighthawk. The general consensus is that the Nighthawk is faster at short distances, the Asus faster at long distances/high attenuation. The Asus unit has known bugs while the Nighthawk appears pretty stable. I got it anyway since I like some of the features such as the ability to configure for 2 separate LANs and it appears Asus is truly working hard to improve it. There are also known to be further improvements in the pipeline such as supporting USB *hubs*, so that it can support multiple drives. But for now I have it configured as an access point only (no router function), 1 LAN, and no media server just to baseline how well it does
On the E4200 (also access point only, no media server) my SP2 used to get a lousy 65Mbs link, and then after an SP2 upgrade it dropped to an even worse 30Mb. Connected to the Asus 5GHz band my SP2 now links 270Mb in the same room, 217Mb (worst case) 100 feet away through six walls and two floors. Reads and writes to my server (Ethernet, no WiFi) are WAY faster than those numbers imply. Even internet access - which should never have been much of a problem given I have DSL! - has notably improved. Latency is more than half on average
I am happy.... mostly. The Marvell phy is still junk, but it is now tolerable junk. Every device I own that has an Intel phy is linking at 450Mb and hardly degrading no matter where they are located
Add: I currently have no AC clients so I can't speak of its performance in this regard
