When choosing overly bright lights (either headlamps or rear-facing), remember one fact:
You're shining a flashlight in someone's eyes. Do you want them to see you? Because getting the brightest thing on the market to blind them with, is not the way to prevent you, or more likely pedestrians, from being stuck by people with spots in their eyes from your lights.
Code of Federal Regulations for automobiles even states that headlamp bulbs should be no more than 3000 candela, and no more than 5000 kelvin temp for this reason. Rear facing lights (except brake lights) must be a red color, and they have less candela (not sure what it is).
Do any of you know why red lights are rear facing? It's because the red spectrum doesn't dilate your pupils as much as a white or yellow light, preserving your night vision. It is also why many street lamps used to be an orange or almost magenta color. It helps you preserve your periphery vision, which allows you to see things like people about to cross a crosswalk, so you don't strike granny down in a fit of Lumaniacal Glee because you've shot down your own night vision.
I keep a signalling mirror by the wheel. Whenever I see one of those high-intensity, super-bright, purple/blue tinted pair of lamps, I directly shine them back in their driver's eye. I'm done playing games with almost hitting people head on because I cannot look forward.
Sorry to rant - but getting 'the brightest' of any lamp in your rig for exterior lighting is dangerous. Flat dangerous.
