The problem is with mechanical devices is yes they to offer some level of security, but with the likes of Lidl and Aldi selling battery powered power tools etc, they can be overcome with time. You also have to consider moving the vehicle in the event of an emergency.
With Tracking devices the crazy part there is again these can be overcome with signal finders and blockers (all readily available on the net for very little money).
It is a difficult one to balance as to what is the best route to pick, but we have seen a massive interest in customers upgrading their existing Strikeback/Growler alarm systems with our Non-Starter remote immobilisation systems. This not only offers detection of any blockers/grabbers, but even with the thief having a Bypass or stealing the m/h keys from the house, the vehicle has been immobilised with an independent system which compliments our Strikeback/Growler systems.