I do. I use a Planet Bike Better Beamer 5


In the flashing mode it lasts in the tens of hours and I use rechargeable batteries. It can be seen half a mile away.

Moreover, it can be seen by cars preparing to cross an intersection, when I have the right of way. Many times I can see a recognition reaction in their face,

'hey, this hi viz yellow blob and the flashing light is a cyclist and I have the STOP sign...'

For the back I have a Turbo Flash LED



This thing you can't ignore in the brightest daylight.

Better noticed than dead...