The most advantage I have seen from one of these devices was with vintage gear. The usual cloud street, fast head on scenario. Worked great!
The old OzFLARM gives indication with a two-color LED circle for horizontal relationship/distance and three LEDs for vertical relationship. Collision potential gives an alarm sound. Primitive, but effective.
For reference, a video of another OzFLARM with collision warnings when we moved close:
https://www.youtube.com/watch?v=rgxqWPiR6lE
Verbal audio warnings in the latest versions are an excellent addition to that.
Lately using audio only, so to me stealth mode sounds great.
Jim