I noticed there was also a newer thread (around a year old) on this topic. It seems that what Nicolas Goaziou proposed earlier (about using #+attr_latex to modify whether a latex block is a header block or not) has not yet been implemented. This would be an alternative, though I find it more cryptic than just having a #+begin_latex_header block, so it would probably be more difficult for org-mode users to find (or remember) this, and as I mentioned in my last message, it lacks the benefit of consistency with how #+latex and #+begin_latex relate to each other.
Nicolas' message is here: http://lists.gnu.org/archive/html/emacs-orgmode/2014-06/msg00841.html.
