Lights don't cause herms, improper puning does. A watt is a watt imo. I have used them all, cobs, cmh, strips, qbs, hps, all that shit will grow plants like weeds if everything else is dialed in. I personally think alot of growers put to much stock into lights and let the more important issues suffer. So many mediums to grow in, they all have some kind of advantage or disadvantage. I'm using 750 double ended hps right now and like them a lot. 2 of them on a 4x8 dimmed to 600 is giving me killer results.