when i was using hps/mh i ran 2 600 watt hps, then 1 600 watt hps pluss 1 600 watt mh, then ran 3 400 watt, 1 mh 2 hps,, all over a 4x6 table.. the best quality and yield was under the 3 400's.. i suggest a 2 to 1,, 2 hps for every 1 mh if your after a balanced spectrum,, the 1 600 hps and 1 600 mh had the lowest yield but quality was good..
i have since switched over to cmh,, my gram per watt has increased and quality is also way better...
as for led,, i know very little,, but im interseted in saving on electric wile keeping yields and quality..
i was using 3 315 watt cmh lamps above the 4x6 table 945 watt total and averaged over 3-4 runs a 1.5 gpw
then i bought 2 100 watt go green citizen cobs,, and ran 2 315 watt cmh and 2 100 watt cobs, total wattage 830 watts over 4x6 table,, ive only finished 1 run,,, and on the second now but yields under the 830 watts hit 1.5 gpw on the first run,, i know im only saving 115 watts but so far the led has impressed me...cmh = 3100k, 100 watt citizen led= 4000k,, nice spectrum