I honestly dont get why King is so pissed. He's changed in the year I've been gone. My biggest issue with his nonsense is the "science" he's "referenced" without actually naming any laws or studies.
As far as heat, yes 1 watt is 3+ BTU, but LED give off more light per watt used, that is to say less energy is made directly into heat. Duh. For real.
LED has it's drawbacks. Coverage footprint, cost, and assembly are among them. I'm seriously considering spending around $1000 ona QB setup so I can run two tents. Why? Because of heat and space, the 2 biggest draws for LED. My ceiling is just over 6.5 feet, and will get smaller depending on how I build my room. (My floor gets water, so I'll likely have to elevate the room)
HPS is great if you have high ceilings and need to cover a large area or have low ambient temps. Why? Bigger footprint, more space for heat to dissipate, etc. HPS costs less upfront, is more readily available, has a great spectrum, and is a proven grow method with a huge community of growers who know how to perfectly dial in a room. THIS IS WHY COMMERCIAL OPS USE IT.
CMH is becoming popular because it's got a great spectrum and is more efficient than HPS with similar operating requirements.
CFL nobody uses these except for newbs and budget dudes, but I shit you not, my brother in law had an 8x8 running CFL and grew some dank ass smoke. He probably didn't yield anything close to what he could have with "proper" lighting, but stuffing enough of these in a space will get you smoke.
Stop bashing each other and actually take the time to have a discussion about the pros and cons. Stop telling people that they suck at growing because they don't like your preferred light.
And for God sake, King, NOT having LED makes you BIASED TOWARD the light you do use.
EDIT: I'm also considering picking up HID equipment for the winter months because here in New England we have the worst of both worlds. Hot as balls with high humidity in the summer, cold as fuck in the winter.