I am using 11" on my rack and it is daisy chained with a 12" section at each level. I have always been concerned about it because of some horror stories I have read. Just talked to a friend and he told me all of those stories are due to people not using a thermostat. Is this correct? He also stated some were also misuse of the product and that it is a very safe product. Anyone on here have a bad experience with it?