The answer is easy. Use two. One flashing and one steady. Then you're covered both ways.
+1
Flashing light gets attention.
Steady light gives relative velocity and location information.
I run both flashing and steady in the back and flashing and steady in the front (both daytime and nighttime) because I want to be seen and I want them to judge my location and velocity as accurately as possible.
I run two battery chargers at my desk, if that's an indication of my commitment to the idea.