UL ratings are misleading. Just because it is UL cert'd doesn't mean it won't burn your house down. It does decrease the risk slightly, but a poorly built unit can easily be listed as UL. I believe Mike is correct. The problem is ballasts can easily overdrive the circuit on a bad connection or arc to another so the unit can burn up fast. At these wattages, any device is a fire hazard IMO and I wouldn't recommend a product that has a history of poor construction. Design wise, I am sure they are fine but quality of construction is important to me when it comes to losing everything in my house. Is a couple hundred bucks worth the risk? Maybe, but not to me.