I think the debate between HIDs and LEDs is about the same as having a debate between which is better, a tractor or a jetboat. Both are modes of transport but a jetboat cannot assist you in feeding out hay to cows, and a tractor is shit at helping you score chicks.
The debate really should be between LEDs and CFLs because they occupy the same space - a lighting system that is great for using in confined space grows.
Lets for example take a scenario of a grow space that is 2ft x 2ft by 3ft high. Firstly you wouldn't even consider using a 400w HPS in there because for one the light would take up half the space, and secondly there is no way it could work without cooking your plants. So then the debate would be between CFLs and LEDs as to which would give the best results.
Scenario two is a grow space that is 20ft x 30ft x 10ft high. A Large grow room. Most sane growers would not even consider trying to light that area with LEDs due to the cost. The only time fluros would be considered is if that was an area dedicated to vegging alone. The only really honest debate would however be between whether or not a series of 400w, 600w or 1000w HID lights would give the best results.
Lets run another scenario. A table that is 6ft long, 3ft wide needs lighting. The plants on the table are clones in 3/4 plastic bags. The most efficient lighting systems would be lights that a low watts and cover a wide space with even easy lighting that does not emit too much heat. Again the fluros and the LED systems would be the main center of discussion as they are generally flat area lighting systems, extremely efficient at dispersing light evenly over a wide area where penetration is not a factor.
Running costs, keeping power bills low, are a bit of a faux argument in my opinion when trying to do a complete grow with CFLs or LEDs, well, from what I have seen. Your typical CFL grow starts with 4 x 20w CFLs but ends with 10 x 40w cfls placed all around plants in order to get decent buds. Well 10 x 40 = 400w so there isn't that much saving between that method and just purchasing the one 400w HPS lighting system and using it from start to finish.
The claims of a 1:4 watt ratio between LEDs and HID systems is crap. During veg you can run a lighting setup much less than what most growers use and still get a good veg behind you, so yeah a 120 watt LED light will give just as good results as a 400w HID, but, that all goes out the window when budding. LEDs at a ratio of 1:1 during budding never give the same results as an HPS of its equivalent unless the grow is specialized to suit the low penetrating LED lighting, but even then the buds are never as dense as the HPS light grown buds.
The other thing that doesn't help LED campaigners are the sheer amount of fake LED grows, grows that have been assisted by other lighting systems in order to get similar results to HID grows, and secondly the amount of LED grow journals that are not completed, for reasons one can only assume to be grower embarassment at the spindly fluffy results of using what is a good cloning and vegging lighting system to grow buds.
