The EverLED's don't overdrive the luxeon at all, and in flashlights without enough heat sinking ability they will drop their brightness a little bit more to keep from over heating. but they are still plenty bright! I've had mine for several months now and I use it in a light with no metal heat sinking at all and it continues to work very well.
As a simple drop in mod for almost any flashlight I think they are great. Make your Maglight into something more interesting /ubbthreads/images/graemlins/smile.gif
You do have to be careful though, there is extensive detail on this in other threads but they have no reverse voltage tolerance at all. It turns out many flashlights are actually wired backwards for one reason or another. You really should check to be sure that the center tip is positive and the outer connection is negative before dropping in the EverLED or you will blow it up. ("blow it up" is a technical term meaning it stops working in a hurry, it does not necessarily imply a spontaneous kinetic disassembly of the device)
You can use the cheapest meter from radio shack to verify that, and if you're posting here you should own a meter anyway /ubbthreads/images/graemlins/smile.gif
I actually wired mine up in a backwards flashlight and when it didn't turn on I switched off immediately and it was not damaged, but any more time than a second does burn them out...