got one that came fitted to the car (and in my last car aswell) and didn't bother activating either of them
i spoke to one of the insurers about this when he asked me if it had one and basically told him if my car gets stolen i would rather i didn't get it back tbh, he agreed and basically said that the price you'd pay for the yearly subsciption would more than likely be more than you would save of the insurance anyway
sorry misread the question a bit (missed out it's only the stickers your asking about lol), yeh i would put them on, in the end of the day if they know how to disable a tracker then their going to steal your car no matter what anyway, would help them possibly being caught though if they didn't know but would you want the car back ?