I'm looking at adding a 2nd HPS to my grow room. Currently have a hydrofarm 430 watt HPS overhead, with rows of T5's for side fill lighting. However I'm going to lengthening my room and was thinking of the 600 watt Digital Greenhouse Ballast for the other light source. I used HTG many time and have no regrets. Just not sure why their ballast is so much cheaper....kinda makes me worried.