You're asking in the wrong subforum.
pfSense is a turnkey system based on
FreeBSD, and is dependent upon one of the FreeBSD
forks of PF. There were two: FreeBSD 8.2's PF syntax is equivalent to OpenBSD PF at release 4.1, and FreeBSD 9's syntax is equivalent to OpenBSD at release 4.5.
I've never used pfSense and have no comment on it.