For the compiler issue see
http://www.mail-archive.com/misc@ope.../msg49069.html
Also see
http://en.wikipedia.org/wiki/GNU_Com...e_alternatives
OpenBSD doesn't use the latest and greatest gcc, because gcc developers, mainly from a couple of Linux companies like RedHat, have dropped support for some hardware platforms.
Why should a company like Redhat sponsor gcc development for hardware which are for no commercial value for Redhat?
If OpenBSD still wants to support these for gcc obselete architectures, it has no other choice then using an older gcc version.
IIRC NetBSD is dealing with this unfavourable condition by using several gcc versions.