With the blackjax I think you have to put in a PIN number with x minutes of driving orbthe car just stops, I wonder if that would become a pain? Great idea though as the crim drives off without any grief with you if they nick the keys but they then get stranded not far away. I have considered it.
the thing I don’t like with many modern systems is the manufacturer is after a monthly or annual subscription. I was looking at the home hive systems and they are the same.