if it's brighter than a dinotte tail light, it might be a good thing that there's no strobe or flash mode.
anyone who's been behind a dinotte tail light can attest to that.
solid/steady on will give drivers a better perception of how fast they are gaining on you compared to a blinking light source. one reason why I like to use 2 rear blinkies with one on flash and one set to steady.
IIRC the DiNotte is 140 lumens, which is well more than the flashlight.
FWIW, I use flashlights for my front lighting and couldn't be happier with them, but I just don't see this as being a good taillight due to runtime, mounting issues, and lack of a strobe or flash mode. Hopefully someone will come out with a self contained light to rival the DiNotte....