Interesting again - the video comparison I saw had 600W HPS lamps alongside 268W LEDs in a commercial set up in the USA, and there was no noticeable difference. The anti-luddite in me wants to say that modern LEDs are of sufficent quality to be suitable replacements for HPS lamps.
I am not the most experienced grower though and as I say, no first hand experience of LED growing.
I would like to know your rationale for concluding that a 268W LED is the equivalent to a 268W HPS? Whilst I accept LED's have undeniably less light spread overall, ergo a more concentrated area which is perhaps more suited to sativa over indica strains, I believe the actual light output in terms of lumens is equivalent. Since the electricity input is by and large irrelevant, and it is all about the efficiency of the bulbs output, what evidence do you have that a 268W LED is not as powerful as a 600W HPS? A lot of those 600 watts is lost to heat output, which is entirely wasted energy?