I would stay away from the knockoffs as well!! The blackstars are great lights!! I have been using for some time --over a year now without any issues. Well, my biggest issue is that 1 light will veg a plant bigger than it can fower,,lol. So it seems like each plant is taking a light and a half to flower. Under the 500s. You have to get the right size light based on your expectations. As far as led technology goes.....its here and it works. There are plenty of journals on the net. The problem with most of the journals is the the growers are buying the smaller lights and getting great results as far as quality, but some complain about their yield. I have found that the blackstar 500 gives results equal to and better than a 600hps. The 900 blackstar--well, there are no questions, unless 8-10ounces a plant is an issue with you??? lol And maybe more with different strains. This light will produce,,,,,if you're expecting to just throw leds over your grow and compete with hps lights----good luck. It takes some time to figure out the light heights, plant numbers, coverage area, etc. I realize the cost of the 500 and 900 arent cheap compared to hps lights,,,,but you wont see me buying anymore bulbs, ballasts, multiple inline fans, and this list goes on about how easy things can go with the right size leds. My return on investment has been 3-1. YOu will meet your expectations and you will have your patients wanting led smoke before they take your hps smoke. Its weird how they can tell somethings different. I just havent told them what....haha. Anyhow, i need to lay off the wake and bake some...lol. Wonka