i didnt do a comparison test. yes, i did try to compare with 1 photo, but there were things that werent right at that time. my HPS bulb was waaay past needing to be replaced. i had other strains going under the HPS and only one P.Rain. it got pushed aside by the DPDs and i didnt end up harvesting much from it, hehehe. i also didnt veg with the last unit, just flower. i ended up with 80 grams, tightly trimmed up (im very anal). its looking very nice this time around. stay tuned for my next test. i will be doing a side by side 'watt for watt' comparison with 2 LumiGrow ES units against a 600w HPS. i cant wait, should be off the hook.