The Public Safety department at my college has Stalker ATR's which they leave in constant on mode. One car had it on all day so I did two real world runs with my V1 3.858.
1. First time I was doing about 55 or 60 and got four bars and then it went to full strength and I saw him driving towards me. It didn't allow for much time to slow down, but it was around a curve, so I guess it was ok. I still would expect more warning time...
2. I was getting no alert in the setup in the picture until I made a right and he made a right to follow me. The scale is in the bottom left.