I've got a road-angel, the one called "new", but isn't any more!
It's fine, but considering the money my little tom-tom is better as it's a sat-nav as well. Hence the expensive road-angel sits in a box unused. [&o]
Road-angel has the additional feature of detecting laser-traps, like hand-held or Scamera vans. Bearing in mind the very remote chance that the tiny beam will hit the box, it never did on mine, and the fact that by the time they've zapped you it's too late, I can live without it.
The newest generation have "live" warnings of mobile traps. This seems to depend on you paying to keep it updated and everyone has to enter new speed traps as they pass them. I can't see too many people taking the time to do this, let alone the idea of pulling over to do it safely. As such I think it's dubious how efficient this will be.