Just got my RTL510 this week and i general i am very happy about it.
But i dont understand that there is not a option for no light / no flashing when you ride at daytime. A mode with no light would be great and even better if the mode would make the light flash only when detecting cars from behind.
The original Garmin radar shows with its led lights when a car is closing in from behind. This is a nice feature when riding in groups because it not only alert the owner of the radar but also the guy/girl behind him/her.