I've done a few rides with the radar-only Varia now and it certainly works well.
One of the main benefits is the ability to use much more of the road with confidence when nobody is around, without sticking to the side just in case.

The only time I can hear a car before it gets picked up on the radar is in the hills where the road twists so tightly that a car is pretty much on your tail as soon as it is in line of sight.

I've also tried it with the RWGPS phone app and counter to all previous reports/complaints and their own current user guide pages where grey means no cars and green counterintuitively means cars, the display is now green when no cars are around and then goes orange (cars) and red (fast closing speeds).