... because Apple obviously didn't! You get the circle/slash like trying to boot from an unsupported OSX install with a too old machine. I did 3 clean installs to verify this wasn't a red herring. Two different machines as well. Wow... Personally, I use CCC for backup needs. I only discovered this after someone alerted me to it and I tried it on my machines. This is really starting to feel like the end of Apple and OSX.