Going back in time to a bigger hard drive
I installed Mavericks (10.9) on my Macbook Pro and wanted to move back to Mountain Lion because I was unimpressed with the Mavericks system. My time machine backups didn't work, so I decided that the only way I could go back was to do a clean install. I figured, if I'm going to have to start fresh, why not start fresh with a newer, faster drive.
The repair was flawless. I finished it the hardware portion in about 15 minutes. Thanks for the extremely detailed guide :)
If you need to do a clean install, check out the program called Lion Diskmaker (or Disk Maker X) from http://liondiskmaker.com/. It took the Mountain Lion install file I downloaded from the App Store and created a bootable USB drive so I could do a manual boot from the USB drive and install the Mac OS X software.