I considered the X8, but after having used various Netgear stuff in the past with issues, I decided to try another brand for a change: Asus. While my relationship with Asus is also a love/hate one, I had never used their routers before, so I thought it time to give them a chance.
I replaced a 300N Wi-Fi network powered by a Netgear and a 500mbps Powerline network also 'powered' by Netgear with an Asus RT-AC5300 router as main unit, and an RT-AC88U as 'bridge' unit in my home office (Wi-Fi --> 8 port ethernet).
The main difference between the two units is that the AC5300 can power two 5ghz networks and has 4 ethernet ports, while the AC88U only has one 5ghz network and has 8 ethernet ports. Otherwise, they're identical to eachother, and to the X8. 2100mbps per 5ghz AC, and 1000mbps on 2.4ghz N. One of the 5ghz networks on the AC5300 is used exclusively to connect the AC88U in bridge mode, which works rather well.
From the two far corners of my apartment, approximately 50 feet apart, with the main router in a third corner, the network manages over 300mbps actual throughput on AC, and 70mbps actual throughput on N. This up from a previous maximum of about 30mbps.
300mbps is more than enough for my needs. For the first time ever, Wi-Fi has done something other than disappoint me. One for the books!