I was able to standby and successfully change over, not once but TWICE this year to the earlier flight from NRT to SFO without any additional fees. On the other hand, a 1K friend of mine just tried to standby yesterday for the same earlier flight and was told that "yes, you may, but because of the rules of his fare, there will be a fee of $150 to do so". He opted not to go earlier and answered emails on the computer in the NRT RCC.