I use the LED MomentFlash app constantly at work. Its better than my real flashlight (which is not LED). I have used it for up to an hour on the first click setting. I noticed before that when I left it on the second intensity it would actually show my battery was dead within a few minutes.. but i would reset my phone and it would read the battery as full again. It was strange.. so I just used the first click setting.
I havent had a problem at all other than that. Now that I have the CL14 update.. I will try using the higher intensity more often to see if it still drains.