I think when one focuses the right attention to a grow, and has mastered all the techniques to achieve massive yields from x amount of sq ft. LED's could and prob would topple HID's. Only in terms of dollars saved per kilowatt hour and maybe bulb life, etc. Depending on where you live, like here in WA, cooling with AC or moving air with fans is a minimal charge as its just only needed for 10% of the year, if at all. With that said, you can only achieve record yields vs killowatts used by doing SOG. As PJ stated over at Cannetics. This in turn brings other problems. You need legions of plants to run single cola plants filling a space. Even with no veg time, you will be over 99 plants in a blink, very dangerous territory.
But I can also do SOG with 100's of plants, no veg time, with HID's also. Does it makeup in dollars spent on killowatts, with LED's vs HID's, well yes. But that dollar amount spent takes quite along time to make that margain up.
Example. I spent $44,387 dollars to build the new restaurant. All that cost rolls into a opening cost, not a monthly P&L for my food costs. Will that 44k be made up over time, yes. Same goes with this argument. Its all relevant.
Yes over time, the LED's will topple the costs of running HID's. Your off the map for power usage, but still have 100's of plants because you must run a SOG to maximize the light.
I remember before the crash there was a thread with the EffinG asking me for a breakdown of my cannabis cost(overhead). I listed everything out, plain and simple. I explained you only count what your operating costs are, not your opening costs(set-up) as those are not the same. At the end of the day I was paying about, $5.50 per oz, net cost.
At $5.50, trying to lower that using LED's becomes just a fun game of how low can you go. I mean $5, is darn close to bottom line for top shelf. No?