Thanks again for the replies everyone. I'm learning a lot (and reading Mastering pfSense to try to get the best out of it). I'm currently considering upgrading the APU2C4 to a Dell PowerEdge T20 (Xeon E3-1225 v3), which should handle our line speed for VPN easily. The APU handles our 200Mbps ISP speed (no VPN) without even breaking a sweat, just a few % CPU, but it'd be nice to offload the VPN to the router/firewall rather than having multiple locally connected clients at home.