I’d go so far as to say that you shouldn’t touch a FreeBSD or OpenBSD install unless you’ve already done and maintained a gentoo, arch, or LFS install.
And by "post install configuration," I mean adding XFCE or other DE or WM, along with whatever apps you like. No tweaking needed to close security holes.
I’d say it’s about equivalent to a simple Arch install on easy hardware, although OpenBSD comes with quite a bit more security stuff pre-configured.
While you're doing the initial configuration, you get to learn a good deal about what the OS is made of. I found investing a little time to get familiarized with the system components results in more confidence as a user, rather than simply letting the OS do its magic and then wondering how it works later on. Like moving into a new house... You want to know where the fuses are and how to shut off the gas valve.