[...] Maybe OpenBSD could create a section on their web site that provides documentation on the advantages of BSD over Linux as well as some advice on how to avoid common pitfalls that Linux users typically make in BSD. [...] In any event, I'm curious to see what I'll miss coming from the Linux world after spending some time in OpenBSD.
On a semi-related note: what's with replacing nginx with their own http daemon? Is the NIH syndrome spreading to OpenBSD as well?
Nope, they have explained at legnth that nginx was getting too big, and its developpers too unresponsive, for it to be a part of base anymore. That was also the case with the previous web server, which was an old version of Apache with a lot of patches.You can still install nginx from ports though and Apache is in there somewhere as well.
As far as documentation is concerned, please refer to the OpenBSD FAQ:
What will you miss? Probably not much, except for the eye candy. OpenBSD is a really good and complete OS, and its quality is excellent.