You guys are all spot on, it really just comes down to the amount of photons the plant can use in a said time frame, as long as they are getting as much as they want your good regardless of the means, hps,led,mh,cmh will all just give you different phenotypical expressions of what you've got, and as long as the math in your light energy is right you should yield very close to the same in all the situations, you'll just have the different types of nuggets from each due to how the plants processed the spectrum they were receiving, only catch is we have to optimize the spaces for each setup since they all act different, and I think that is where the yield differences come into play just my opinion ✌✌??