My personal opinion; if you are turning it down for the ripening stage, yield losses would be negligible. If you are doing 12/12 you are already giving it more light than nature would, if you averaged out it's flowering cycle.
Another option, which is what I do, is to keep it at full strength, but run 12/12, then to 11/13, then for the last week I do 10/14. This mimics at least the way the light changes in nature. When I factor in all of MY variables (I run co2, I'm LED & vertical CFL) I seem to do better this way than with a constant 12/12 throughout.
I think part of what allows me to do this is I run a lot of light (1250 actual draw, 4 plants) so when they are on, the plants are getting tit loads of light. You could try full strength light & vary the time. Or, you could really mimic nature & ease off on intensity & time.
In my own little experiments, I've found that I yield more keeping full intensity & just adjusting timing. But I don't have the ability to adjust output the same way you do. I have to lose some of the vertical lighting to lower output, which takes away from the lower buds.