So far, my beardie Gizmo has had no problems with his powersun. There are no branches and such under it so he can't get close to it and there are two hides in the tank, though he doesn't use them. He is very active but does choose to rest under the powersun rather than the heat light most of the time. The only time he goes under the heat light is if the room is chilly and after he eats. Then he is under it for an hour or so. I only leave the powersun on for about 9 hours. The heat light is turned on at 10am while the powersun is turned on at 12pm, both are turned off at about 9pm as that is normally when he starts getting lazy.
I haven't had problems so far, he is doing very well. But after reading everything about the powersun, I will be keeping a VERY close eye on him. If I see any problems that were mentioned here, I will be getting a new UVB bulb.