Of course it's a valid comparison. What he says is true - pfsense requires significantly more powerful hardware. The USG doesn't do much more than the ER - The USG is a router as is the ER, in fact it's almost identical to the ER in hardware and OS. The only real difference is it uses UniFi to control it, which is nothing more than a fancy centralised GUI front end. It doesn't really do anything the ER can't other than a few features which are essentially UniFi features rather than features of the USG itsel. In fact it has quite a few less options in the GUI than the ER that instead need the use of a command line to function.