Heres my bit for what its worth. I got my tracker for 2 reasons.
1 - I dont care what condition I would get my car back in but I would feel better knowing that the scum bags did not get away with my pride and joy.
2 - if you are getting one fitted I would only choose the Tracker Response option. This is the top of the range one. I like it simply because it allows me to log in online and view my R32 location any time day or night 24/7 anywhere is goes in Europe.
So if its stolen not only are the Police and the Tracking company looking for it but so am I. I can watch it on a real time map and have as many of my mates get out on the roads to follow it

It cost me over 1k but for peace of mind I was happy to pay that. It also maintains a history of where you have driven since it was installed so you can go back and see where you have been at any time. When you are driving it also logs location and speed every 5 mins. If someone else is driving it (eg if it were stolen) I can request a postion every second (ie real time) if I wanted to.