I can't really see a justification for turning my Mini off. Based on this document provided by Apple:
http://images.apple.com/environment/reports/docs/macmini_oct2012.pdf
The 2012 mini's are using roughly 1.24 watt/hr in sleep compared to .26 watt/hr off. So yes, it uses 5x the amount of energy in sleep compared to sleep, but even in sleep it is going to take 800 hours (or 33 days) before you use a full K/hr. For me, that means if it sleeps for an entire month it cost me all of 11 cents. I know that many of you have higher costs for energy, but the ability to have near "instant" on is worth it to me.
Heck even at idle, this document states it only uses 10.3 watts so I could keep it from going to sleep, and still only use about 7.5 K/hr (83 cents) for the entire month....