Why not? It’s perfectly adequate for my uses at home. Provides me with a single admin interface. I did have an EdgeRouter but eventually went back to the USG.
Ask yourself what additional useful features the UDM Pro is giving you over the USG? Three years ago UBNT effectively stopped developing the USG line because they said it was a dead-end. A mish-mash of code. The UDM line was supposed to be the new “clean sheet” design that would allow their new router/security superstar head of routing dept. Chris Buechler to bring something approaching pfSense to the UniFi controller. By any sensible yardstick the UDM line is a failure. The original UDM was nice. Flawed, but nice. The UDM Pro was launched to huge expectations which it has soundly failed to meet. It needed Beta firmware just to work for over a year after it went general access. The UXG Pro has been Beta for nearly two years and now the UDM Pro SE is just another diversion from the fact that Chris Buechler has utterly cocked up the UniFi routing division. After 4 years of promising the UDM Pro finally got Multi-WAN interfaces, but only on DHCP connections. If you have a fixed IP or a PPPoE authenticated ISP connection it still doesn’t work. Ask yourself honestly what extra features your £350 for a UDM pro will get you and then by all means keep your USG. At least that’s stable.