I've got a few dozen businesses with PFSense with LTE backup, and at this point I'm looking for alternatives. I've considered IPFire, and I've looked at VyOS, Untangle, and OPNSense, but I just recently realized I completely overlooked OpenWRT, which I already happen to have many positive experiences with.
Long term I'm thinking I'll move things over to ARM/MIPS based routers running OpenWRT, and where needed I'll use x86_64 boxes with OpenWRT (eg: Tor Relay at home) as when things break on OpenWRT, its a lot less bad than on BSD.
In particular, I've had issues with BSD taking forever to boot (waited 4hrs at 3am once), deciding it needed an Intel NIC firmware when it had no Intel NICs, thus causing an outage while I drove down there with a WNR2000v3 running OpenWRT, and LTE backup interface handling being poor, whereby the cellular connection will go out (and we'll send a command to the SOAP API on the modem to reconnect), but PFSense needs to cycle the interface for some reason when it already has an internal IP from the modem. Combine that with having to walk customers through any one of these scenarios every few months over the phone, and its a joyous situation.