Sorry I've not got time for a detailed answer to the whole mail right now, but updating one port to -current without also updating dependencies is often going to fail (especially for things like this which have many dep's). Since 5.2 there has been quite a lot of cleanup of system headers, so various ports have had workarounds removed so they're unlikely to build on 5.2 without a lot of extra work. This is why developers will often recommend just moving to -current; and that way if the problem still exists, you will be running the same OS/package version that others can easily obtain themselves making it easier to work on a fix.
On OpenBSD -current always ought to be (and in general is) at least as reliable as -stable (and often more so). The naming "-stable" is intended to imply "stable api" / "very conservative changes only" rather than "stable" as in reliable. This is not necessarily the same meanings as given to the words in some other OS. Things I'd point out, - if this was an upgrade rather than new installation, make sure all packages were upgraded together; mixing and matching between versions rarely works well - the symptoms might suggest some kind of X/display driver type of problem, so more information about hardware (dmesg) might be helpful
