alt Hacker NewsI'm grossly generalizing here, but it seems like OpenBSD boxes seem to be commonly used for the sorts of things that don't write a lot of data to local drives, except maybe logfiles. You can obviously use it for fileservers and such but I don't recall ever seeing that in the wild. So in that situation, UFS is fine.
(IMO it's fine for heavier-write cases, too. It's just especially alright for the common deployment case where it's practically read-only anyway.)
I've used it as a mail server, a web server, and a database (postgres) server. It's also my main desktop OS. Did/does fine, but I never really stressed it. I would certainly welcome a more capable filesystem option, as well as something like logical volumes, but I can't say that ufs has ever failed me.
You'll definitely want to have it on a UPS to avoid some potentially long and sometimes manual intervention on fscks after a power failure. And of course, backups for anything important.