I have been using an X300 for years without the DG switch with my cop job. I have not had an ND of light light. The time I did have any type on ND of white light was with the DG switch. I took it off my gun because about 90% of the time my light would go off as I am drawing. The DG switch is nice, but not really needed IMO. I did a low light training exercise at the range and talked about WML. There were a couple of ex SWAT guys on the range staff that agreed with me about the DG switch. If you are going to have a DG switch or and other type of tape switch for your handgun, you need to train with before you go into the field.