Personally, I'd take a pass on the X60 if you're getting good coverage with your existing router.
We've got a mesh system in our house (ASUS XT8). The WAN port is in the basement and now that my wife works from home, she needs to have a better signal on the second floor. We also have a combiner box for our solar system on an outside wall that was sometimes dropping connection when there was only a single access point.
It looks like the X60 doesn't have a dedicated wireless backhaul. That means the mesh nodes will have to contend with devices for bandwidth back to the main access point if you don't want to run Ethernet cabling between the nodes. You might want to consider a product that has this feature, sometimes advertised as 'tri-band mesh'.
The good news is that even if your router stops being officially supported by Netgear, you have the option of installing DD-WRT, an open source Linux-based firmware. ASUS sometimes even takes features from DD-WRT to use in their official firmware releases.