I don't think the 6/12 light cycle thing would work well. From what little I've been able to find on it, it reduces yields quite a lot. However, I've seen a few people say that 10/14 gives the same yield as 12/12 so I think that using the 10/14 cycle but with the hour of dark in the middle of the light period might be the best idea. That gets the power usage down to 9 hrs per day and I suspect that the one hour dark in the middle will actually boost yield. 9 hrs light per day is actually enough for healthy plant growth anyway so I can't see how it could do any harm. Whether or not the hour of dark will boost yield will have to be determined but I'm pretty sure it will. The 6/12 cycle is also a real pain to set up a timer to do, whereas the cycle I propose is the same every day so it's easy.