Motorcycle tracker

I'm considering purchasing a tracker for my toy. I saw the Bike Trac ( Motorcycle security tracking system - Bike Trac ) device at the Excel show. It has two distinct purposes; It automatically records all the journeys the bike makes, allowing you to view them on the internet. You can also download those journeys in GPX format, which apparently can be transferred to various satnav devices. The second thing is security, that if the bike is stolen, it's location can be traced and passed onto police.

What questions should I be asking regarding purchasing such a device? What are your experiences, good and bad, of these types of devices and services? Is there anything else I need to know?