I've been using a rear strobe (an actual Xenon USCG-approved life-vest strobe) for years. Yes, it (the 1-D-cell) is a tad heavy, but I ride/rode on a 55mph two-lane state highway for 9 miles into the rising sun on my commute. Yes, people did notice it, even when coming up from behind and with sun-glare. One battery lasted all year, riding 2-3 times/week from May through August (leaving the house at 6am).

My 'new' commute is 12.5 miles each way, heading in a different direction (tangential to Sun) and have noticed that I need a front blinky since drivers don't seem to notice me. I recently picked up a Nightrider Mako 200 USB headlight. Fantastic!!! Rechargeable, bright. Steady high, steady low, and flashing. great battery life on low/flashing.