The rt1800 can be flashed with open wrt giveing you alot of control
https://openwrt.org/toh/hwdata/belkin/belkin_rt1800_v1
However it seems your spectrum device is 4x4 mimo vs the belken 2x2.
https://fccid.io/VW3FAST5285/Test-Report/Test-Report-5GB1-B4-4851412#google_vignette
So aside from the improved control it would be a multi client wifi performance downgrade.
The belken should beable to nat you connection. So the main difference is control or extra wifi bandwidth between multiple devices.