Back to reality... Let's suppose I have very old OpenBSD box like it was written.
Usually data should be OK (ftp data, web data, DB data dump??...), but can I just copy for example /etc/master.passwd to a new fresh installed 5.5-current? I'm asking because one had to regenerate /etc/{pwd,spwd}.db files (http://www.openbsd.org/faq/current.html#20130813)? I think upgraded one by one is bizarre but one should know what part of OS was involved in old data, so he can be sure such old data are still usable. Any advices where one should be careful if one is trying to import data from very old OpenBSD to latest versions? (In current.html there's at least rrdtool, but are there any others?) jirib