I have used this hard sleep mode for 8 hours activating it everytime i stopped using my phone. with moderate usage my battery % has dropped from 50% to 43% in eight hours. That means avarage battery usage has been ~1%/hour. This would make my battery last for 5 days with moderate usage (phone calls and text messages). that is absolutely huge improvement!
I´m also using modified kernel(cpu idling @ 125MHz and peaking 500-900MHz on usage)