I haven't seen any signs of the tops burning. My girls are all green and look happy. I've been doing alot of lsting and the girls luv it. in doing so i have been able to create more space between the tops and the light. Also, it is opening up areas of the plant to light thus working on the lower buds. Looking good. Can't believe how much I can bend the stems. At the end of 2 weeks flowering my girls are getting real hairy. Yum!