It would be useful if the tracking company would release a map of low/hi range areas.. however, I am guessing this would probably benefit the theif more than the owner.. but it would be always good to know that your car is in range of the tracking company.
In regards to quicktrak, one of my dads friends had a large ownership in the company (probably not anymore due to the ****ty share prices) and the way he described the system was that the tracker is actually very very small and on every install it will be located somewhere different -- obviously this is up to the installer / customer as well.
The impression I get is that if you have quicktrak, the only way it can be stolen succesfully is if they somehow know where it is installed (inside job) or they know you have quicktrak installed and can move the car to where it will be out of tracking range.(inside job / workshop who services car / friends / family etc)
You would assume that if a theif didnt know that you had quicktrak and just disabled your main alarm, they would eventually be caught driving the car , or storing it - unless they are extremely lucky. Also, i think the insurance companies acknowledge this too and sydney people especially see pretty good discounts if they have the system installed.
dave.