i do it, i think it works. I've done experiments in the past on it. same plant, grown in side by side rooms, under two of the same HPS 600hps/mh conversion.
Under magnafication you could tell a differnce of size and amount of resin glands. But in reality it doesent get you a whole lot higher, it looks way danker and is a little more potent but just a tad more.