Thanks Acorn#1. The reason I am doing this grow is to better understand this question. To your point, it would be better for me to be using a much higher powered LED system equivalent to the output of currently most popular HID system people out there are using to get at a true - LED vs HID answer. From what I read here it seems most are growing much larger quantities than I. So it's hard for me to do an apples-to-apples comparison.
I am using an LED light which the manufacturer claims is equivalent to a 250 watt HID light in terms of useful photosynthesis lumens. Does anyone know, is a 250 watt HID a common intensity for a 40 ft2 (5' high x4'X2') grow area? If so, I hope to provide some data from a typical albeit an LED grow.
As for the economics, the light cost me around $100 on eBay (perhaps because it didn't work well
) they go retail generally for around $125 USD. It uses 45 watts (the manufacturer says it really uses like 28 watts in reality?). So at the least (250 - 45) 205 watts per hour savings times whatever your rate of electricity plus the cost of expelling the heat plus the bulbs (LEDs last forever) and so on.
The real question: does it grow dank in sufficient quantities to justify not ponying up for the additional cash and heat signature of the HIDs? I'm not saying LED's are the answer, but I want to see for myself. Kaminoan in his post above would disagree with my neutral position.