Based upon what I see everyday, I think that going through intersections is the most dangerous part of cycling.
I've had too many close calls with red light runners.. and the only reason why I am still alive is because of extreme awerness of what's happening around me. You can have the best most expensive lights in the world, but they won't help you when somebody nails you running a red light. If a driver is not aware of an intersection with a red light,then they won't see you, no matter how much lights and reflective clothing you have.