I know that the preflash is a pretty big issue here on CPF, but I don't get it. If it bothers you, there is such an easy fix, just cover the light in your hand etc when you turn it on.
A much bigger problem for me which nobody seems to care about is the startup voltage a circuit needs. Most lights can run for days on low but few people realise that it doesn't really matter if you can't turn your light on. For ex, if your battery is almost down and your running it on low and you turn it off cause you want to save battery, you wont be able to turn on the light again even though that the light would had continue to run for a couple of hours if you hadn't turned it off. In a survival situation this could be crucial. A direct driven light would had crammed all the juice out of that battery. Which makes me think that most runtime test on low levels are not that useful. At least that was the case with my old multi stage lights with circuits like Fenix L2D and Nitecore DI. Has that changed?