A reckless enthusiast might throw caution to the wind, install 10.8 over their existing operating system, only to complain about the rough edges later. An experienced veteran of beta software knows you can’t easily undo an operating system upgrade and prefers to preserve their current OS while dual booting into 10.8.
Depending on your Mac, dual booting between two versions of OS X can be accomplished in a number of ways.
I have it running on an SSD inside an external FireWire 800 case. It is crazy fast.