The first thing I have to think if I want to reinstall instead of upgrade is, how to backup MacTeX & homebrew. I have to consider if it will generate pdf documents correctly. (MacTeX is installed in /usr/texbin/) Reinstalling MacTeX is not that hard compared with reinstalling homebrew. Homebrew, though bottled most package, will take a long time compiling a version gcc with openmp support, let alone recalling who to install. And gcc is not the only thing that need a compiling job. Maybe, years later, I will follow the path of reinstalling or moving back to Linux.
So I compile llvm+gcc often with home-brew, the compile time on my laptop takes total about 5.5 hours. But I setup vagrant and vmware to allow me to automate this all away and create txz's of the install.
And as for mactex it seems to work fine for what I use, though it installs to /usr/local/texlive when I tested it a month ago.
