Also it's a really well trodden path. You aren't likely to run into an OpenBSD firewall problem that hasn't been seen before.

Regarding any BSD used for any purpose, BSD has a more consistent logic to how everything works. That said, if you're used to Linux then you're going to be annoyed that everything is very slightly different. I am always glad that multiple BSD projects have survived and still have some real users, I think that's good for computing in general.