I replaced the stock LED in my SafeLight with a Nichia GS co-W. The tint is a little better, and it is considerably brighter on high.
My wife and I use these lights every night. Using the old batteries from our smoke and CO2 detectors (changed every 6 months), the operating cost is basically nothing. My son uses his SafeLight less often, so he gets the strongest battery removed from one of our lights.
Getting the rubber skin off the light is a pain. But once you get it started, it will slip off fairly easily. Of course, getting it back on is somewhat difficult. The LED replacement is easy once you have the light open. Two screws secure the PCB to the plastic shell. Then it is a matter of removing and replacing the LED.