The point is this, why should a grower have to use additional air conditioning to cool lights when they could use a far more efficient isolated blow through system?
When efficiency is LEDs main selling point it would seem that heat removal would have been better addressed from the outset.
With HID lighting that allows a fan to cool the lights, the AC system load is less. The same would be true for LED.
Non air cooled HID lights are as much a novelty as current unducted LED lights. Unducted fixtures of any type are simply early iterations that need heat management improvement.
Your small two tent situation is doable simply because of its small scale, upsizing that situation would result in an ever increasing need for air-conditioning that is very costly.
It is more cost effective to move heat away from the grow than to cool that heated air, especially when the environment needs to be at a certain temperature that is always below that produced by a fixture of nearly any wattage.
The blow through system you likely use is I assume drawing cooled home air, and while you may not see a huge increase in power consumption from your homes AC unit, it does have to work more because of the heat generated by the lights.
1000W = 3412BTU/hr, LEDs don't avoid this math, so while a 1000W LED may produce a higher PAR reading than a 1000W HID you still need to deal with the heat they generate. Ducted LEDs would be a huge advancement toward stepping out of the realm of novalty and into real useful pieces of grow equipment.
That's my stance, I'm not against LEDs I am simply pointing out a fundamental flaw in the current design of the fixtures.
Fixing the problem is simple, and perhaps the industry will move in that direction in the future. If they did I could see how they would replace the current HID lights most often used.
