Has anyone ever checked how much power a lamp draws? I have and found something very very surprising. I used an amp probe and measured the amps a "250" watt cfl draws and what a "400" watt HPS draws. What came up was the "250" cfl ONLY DREW 0.9 amps@115 VAC the HPS "400" drew 3 amps @115VAC. Using ohms law, the "250" cfl is only consuming 103.5 watts. The "400" HPS is consuming 345 watts. Why are they called 250 watters? This makes total sense because a 8U cfl bulb uses T5 tubes if you were to stretch out all the tubes of a 8U, you would get a little over 15 feet of T5 tubing. A 4 ft T5 tube draws 28 watts. If you take 4 X 4ft T5 you would get 112 watts. I don't believe a "250" watt cfl puts out 15000 lumins though. I believe it is closer to what a T5 puts out which is around 95 lm/w so a so called 250 watt cfl is in around 9832 lumins.
My point is if you want to make a fair comparison between cfl and HPS, you got to use the same or close to the same amount of watts. Most comparison done so far used way to few cfl bulbs because we all believed the wattage on the box. an ideal test condition would use 3 X "250" watt cfl's vs. 1 X "400" watt HPS. All you nay sayers can do this current drw test yourself and see that these numbers are correct. All you need is a amp probe clamp on meter and takes only a few seconds to get a reading.