I have a unit that is GPS Based Called a Snooper it works great for fixed camerasm I did not used it often enough to see how it does in the laser and other bands. They are nice to have for time that you forget the speed limit....epecially if it monitors what the speed limit is.
My problem is that the speed zones sometimes change so often that I forget what it is or if I am in one!! I have a iPHONE APP called navmii/Germany. It is so good that there is no need to turn on the other unit when I am local.