I'm looking for a light set up for my M4. I really like Surefire and I want the brightest, most "wide" light I can get. I found a used M500 with the giant (like 3") head on it, for $150. I'm not sure on the light output and performance though. Anybody like or dislike them? Or even seen one used? I'm open to other options if they are super bright flood style lights. This is my woods/hiking/HD/zombie gun. I prefer Surefire, Insight, or Streamlight. I also do not have a rail to mount it on, amd I like a light at the 1-2 o'clock position or 10-11 o'clock.