It's awesome that cool things from OpenBSD are being ported over to FreeBSD, but why not just use OpenBSD from the get-go? It's already a struggle having to deal with FreeBSD's outdated version of pf.
I've got a lot of love for OpenBSD but I can understand people wanting to use FreeBSD for things like ZFS and dtrace. However for those seeking to use said features personally I would recommend looking at an illumos distro.