Firefox

I have downloaded firefox-xxx.tar.bz2 from the official site and extracted it to separate directories named firefox1, firefox2 etc. I launch Firefox using the script

#!/bin/sh

if [ $(pwd) != "/home/${USER}" ]
then
        HOME=$(pwd)
        echo "Starting firefox from ${HOME}."
	firefox --no-remote
else
        echo "ERROR. Current directory is same as the main Firefox directory."
        exit 1
fi 

exit 0

Been using this way for quite sometimes now for account and cookie separation (yes I know about container extension). Is it safe to do so or should I pass something else as argument for better sandboxing. Also i noticed that, every instances run on the same version as my main properly installed firefox, Does this have something to do with the sandboxing or just a perk of auto-updates?