Solaris' port of PF is not out of date. _And_ they are working with upstream to merge their changes so both parties have a) better code, and b) less maintenance burden.
iianm, Solaris has a port of IPF, not pf. Oracle is working on trying to port pf now.
If anything, this should teach us not to port unportable things from different operating systems, because the maintenance cost is untenable.