How long is long lasting? I ride Audax/Randonneuring and Ultra so this is a big issue for me. My rides often go through the whole night, sometimes several.
The biggest problem with rechargeable/USB is the put crap batteries in them period, they are out of sight and no body sees them, even top brands! Minimum capacity, and after 18 months you won’t be getting a full charge. The best comparison i know of is one light, which i use. I cones us 2 versions USB or AAA battery. The usb last 10 hours constant light and the AAA 40 hours (80 flashing) on a single battery, you get about 30 if you charge your own AAA. No charging time and new batteries if needed at every gas station! I have 2 one on each stay at the back.
Topeak Redlite Aero.
The Garmin Radar is fantastic, the 515 has the best battery, and if you have a garmin headset. you can turn the flashing light off and use a topeak instead. This can add 10 hours for the radar.
Lots if people say, you dont need it, you should always look etc, and yes they are right you still need to look. But its an extra layer and i love it. With near silent electric/hybrid cars, wind, unexpected traffic in the small hours on a Sunday morning, tired, distracted, navigating, coaching or just making a mistake. Its a great tool