I won't pretend to understand light, but I've read a lot of studies on how temperature effects the brains perception of brightness, vs actual usable light. I ride motorcycles, my daily driver for 10 years had two wheels, and in the winter I learned a valuable lesson. The HIDs I retrofitted, while much brighter on paper, and seeming much brighter further out, caused nasty eye stain and less luminosity. It wasn't until I hit something because I just didn't see it in time that I swapped back and looked for answers.
LEDs also throw light where you want it, no need to reflect 50%+ in a different direction. That added efficiency is why I think these are brighter (using a light meter) than $30 worth of HD fixture and 2xT8's.
The other advantage: here in SC it's in the high 40's in my garage. I still have 1 LED and 1 Fluorescent fixture wired to my switch. When I just went to take out the recycling (10 LED boxes) the LED was full brightness immediately. The fluorescent was still warming when I was heading back into the house.
Finally, for those that have their lights tied to their garage door sensors: ballasts don't like to be cycled. LEDs don't care. I've replaced the pantry CFLs every 2 years from the wife and kids cycling it.