Not read the whole thread. I don't use a bike computer, just have free app on phone , 'ride with gps', and I use the garmin radar light - proves its worth on country lanes to see cars coming up behind, rely on it really with wind noise, on single track roads stay in road center until car coming either direction. Its especially handy when riding with company, can cycle along side.
I tend to listen to podcasts on bone conductive headphones when cycling to pass the time, and to also be able to hear surroundings, so the radar is used all the time