Port-forwarding with IPFW / natd

[remodeler]

Is there any reason to prefer port-forwarding with ipfw (forward ipaddr) vs.
natd (-redirect_port), if I am using both subsystems in any case? I see natd
uses libalias and an ipfw divert port, so my thought is that the ipfw approach
would incur less overhead. Also, the ipfw approach permits a hostname for
resolving where natd requires an IP address.

Thank you.