Hello, I was wondering if I use Time machine to backup all from there to external drive. From there does Time Machine let me try new OSX (Mavericks or Yosemite) and then revert back to old OS X version? With all data and software app from the external drive set to Time Machine backup. Reason is I want to see if some software apps work on the new OSX, cause there could be some that don't work properly or launch. I'm currently using 10.8 Mountain Lion - iMac. I would like to update 10.11 El Capitan, but I'm 95% sure some apps won't work. If you guys think its possible to test out, then I would stay at Yosemite or Mavericks.