Just don't bother with the Ducati alarm, it's not Thatcham approved and earns you no insurance discount. I've got a tracker on my GS, it's expensive, (about £600 for the unit, fitting and a 3 year subscription), and it gets me no insurance discount but I always know where my bike is and there's no sign of it on the bike, I've looked and I can't find it!!!! It'll also tell me if my battery charge is low amongst other things.
Yeah, I think its worth getting one of these. The problem is that even after we get that complete system, we have to pay a subscription. But in the end I guess it's better to know if something happens to bike, you will be notified immediately