4-5 years ago I used pfsense as internet gateway and vpn for point to point in an office with probably 20-30users. We had it clustered between a VM (on ESXi) and a physical appliance on alix (if I recall correctly, or another of the supported sff appliances). The VM was rock solid while the appliance from time to time was experiencing issues (stuck/memory exhausted I think) up to the point that DHCP lease were not released anymore and the office was de facto unable to work.

I think at the end we just kept the VM running alone.