IMHO, that doesn't sound like much more than the factory alarm does. I've had alarms on cars in the past and I find they're mostly expensive noisemakers. The flashing light on the (factory standard) dash is probably more valuable than the break sensor and if someone breaks in, the damage is done. Your car shouldn't go anywhere without the chip in the key, so I'd say save the money and spend it on something more tangible.

Eric

'06 Magnetic Pearl HCH w/nav

'04 BMW M3

'05 GMC Sierra 1500 Denali