I think it's fantastic that we are debating which light is best...just by having a working rear light puts us ahead of, oh say, 90% of the cyclists riding around. I run 3 flashing rear lights (PBSF, Trek flashing, Nashbar flashing), one helmet mounted (Princeton) and a flashing bar mounted (Cateye).

I will probably replace the 3 rear lights with a Light and Motion 180 and a ReeLight set. I had the ReeLights on a previous bike and was real happy with them.