The E2D was actually the first tactical light that I had ever heard of many years ago. For a time you could even purchase them in local stores such as Lowe's or Home Depot but the price was astonishing. The Surefire models are well known for durability and the Fenix models are supposed to be comparable in every aspect. That's why I asked about the long term use of the Fenix models. All of the reviews have been great and I recently had the opportunity to test one out. but I have never heard of long term tests, especially to the degree of tests that Surefires have gone through. As was mentioned, the Surefire models have been in use in the military and law enforcement for a long time and have been proven.