That’s more or less what I say, too.
Just do NOT put any “default ROOT” settings in any standard “environment” files.
Every user should always be expected to source an appropriate “thisroot.[c]sh” for the ROOT version that [s]he wants to use.
Note: you can easily create shell aliases for them (and put them in any standard “environment” files) … something like:
alias root-53436='source /opt/ROOT/releases/root_v5.34.36/bin/thisroot.sh'
alias root-60902='source /opt/ROOT/releases/root_v6.09.02/bin/thisroot.sh'
alias root-61004='source /opt/ROOT/releases/root_v6.10.04/bin/thisroot.sh'
alias root-old="root-53436"
alias root-pro="root-60902"
alias root-new="root-61004"
alias root-dev="root-61004"
alias root-5="root-old"
alias root-6="root-new"
Actually, I myself do not put any “default ROOT” settings in any of my private “${HOME}/.profile”, “${HOME}/.bashrc” (and so on) files. I always call one of the above aliases in every [x]terminal in which I want to use ROOT.
BTW. My “original post” contains advices how to “configure” ROOT but they are quite old and suited for ROOT 5 and early versions of ROOT 6 (but not really for newer ROOT 6 versions).