Do I really need to export path in .profile?

Following models provided in various places, currently in my ~/.profile where I have many lines that append or prepend directories to PATH, I also have corresponding export commands, e.g.:

export PATH=/opt/local/bin:/opt/local/sbin:/opt/local/apache2/bin:$PATH

PATH="${PATH}:/Library/Frameworks/Python.framework/Versions/3.3/bin"

export PATH

As I undertand things, the purpose of export is to make a setting available to subprocesses. And my understanding is that PATH is an "environment variable" in the technical sense of the term, that is, it is automatically exported.

So with OS X, is any purpose actually served by having those explicit exports in ~/.profile?

Same question if I moved all the path settings into ~/.bash_profile .