Originally Posted by
Eyes Roll
Your brightest bike tail light that can be seen from a mile away may run out of battery/charge behind your back and turn off without your knowledge, but a safety colored vest will always have your back, providing visibility and safety. You make your call.
A Garmin Varia battery lasts about 10 hours in daylight flash mode (which is seriously bright) and the head unit warms you when the battery is going flat, so that is not an issue.
I rode a sportive event a couple of years ago and at the end another cyclist came up to me and commented how he had been using my flashing tail light as a beacon to chase down when he was over half a mile behind on the road. This was in broad daylight.