pfSense has the ability to do site to site VPNs either with IPSec or OpenVPN. Both are capable of being very secure. But one of the things I like about the OpenVPN site to site is that you can configure a firewall to be a vpn server and the remote as a client. This is especially good when the remote has dynamic address assigned to it. No messing with dynamic dns and you never need to know the remote power IP. It's not that hard to setup and it's a good solution. There are many things that I do like about the pfSense box, and this is one of them.