I often boot from my clone in order to run Disk Warrior on the main drive. I had always done it via the Option key trick (hold Option while restarting, then select the clone and press Return) so that I didn't have to change the default boot disk in the Startup Disk preference pane. I have been using
Quick Boot for a few weeks and it saves a small amount of time.
I can't vouch for its efficacy in anything except OS 10.5 but for me, it works exactly as advertised.