This, or a battery kill switch, is really the only effective theft deterrent. If there is an alarm out there, the chances are infinitely high that someone has already figured out a way to get past it. Its just the way things are.
It sounds like this guy is looking more towards the effective keyless entry rather than super-high-tech alarm mechanism.
I don't know anything about alarms but I agree with Twistedrx7, go with some kind of kill switch in a hidden location (above the dead pedal, for instance, so you can easily activate it with your foot in a seated position) and you will have peace of mind.