I bought this as a replacement for the fr160 - I needed a slightly longer life for the brightest mode. And as a bigger, bulkier fr160 replacement, it works fine - good daytime running light, decent battery life, bright daytime flash modes.

But when I connected it to my Edge 530, everything went wrong.
I can't set a light mode from the head unit, and when I try to connect it next to my Varia RTL515, none of the lights work.
The only thing I was hoping for was automatic start/stop of the lights along with the head unit and battery status display. None of these features work. You can check the battery status, but this requires the light to be connected to the headunit, and when you connect it, it breaks the connection with Varia.
ANT+ is completely useless. I don't think these features have been tested. Do not buy this light if you want to use it with the headunit.

The light itself is built solid as the FR160 was.
I still wish you could screw the male Garmin connector to the top because my Mount has Garmin female at its bottom. I 3D Printed an adaptor so it works for me.
UI:
UI is crappy. You need to push the button 1.5s to turn it on an 2.5s to put it into pairing mode. This is far to close to each other.
If you have successfully paired the light, it will not behave as expected. It will reliably forget its pairing after one power cycle. If it doesn’t forget the pairing, it will override the Edges light control. The Varia Radar will turn crazy and sometimes even gets kicked off the light network.
You can’t change the light pattern through the Edge.
I can’t read battery status.

The surplus charge for ANT isn’t worth a dime, I hoped it would at least show battery status and turn on and off with the rear light. The Edge leverages its light sensor to turn on lights in underpasses etc, not working with the FR300.

I would recommend buying the light without the ANT function.