I would definitely trust what latewood says over me. he obviously has a lot more experience. I only have opinions from my "somewhat" limited experience.

I guess my thinking is that more light is like a hydroponic system. Your putting the plant in an unnatural state, where it is able to uptake far more dissolved oxygen, sits in a constant nutrient state, and the environment is very carefully monitored. This however, does substantially increase growth compared to a normal soil grow. So, to a degree, wouldn't MJ possibly be able to take advantage of abnormally long amounts of light, the same as it is able to take advantage of more oxygen and nutrients with hydro?

Finally, I will stop with saying that my plants, in flowering mind you, grow more during the night then the day. So hey, that backsup latewoods statement IMO.