I'm going to act as the Devils Advocate here.
If you have a vehicle with Keyless Entry & Start I can see the Ghost being useful as this system is easily overcome electronically.
The California does not have this system, it needs the key & chip to start and gain access to vehicle without activating the alarm.
The Ghost doesn't stop the Spare Wheel or Tailgate rack being stolen.
The Ghost doesn't stop the smash & grab thief armed with a house brick.
All it does is stop the vehicle being stolen whilst in pocession of the key remote.
1. How many California are stolen without the thief having the owners key and being driven away? Very few if any.
2. How many Californias are stolen with the thief having the key? More likely than above.
3. How many Californias are taken on a low loader without a key? No idea
4. If the thief gets the key by burglary, what is to stop him getting the code from the owner?
In summary, the Ghost does not stop the opportunist smash and grab thief, it doesn't stop the low loader professional thief and just puts the owner in more jeopardy from the professional gang who break in to take the keys and who might have no compunction in threatening the owner and family.
Lastly, for the more adventurous owner who goes to far flung places you're more likely to find a mechanic you can get your vehicle going than a Ghost technician who can sort out the Ghost if you have a problem.
However, if that's what you need to sleep more easily at night then so be it. Personally I prefer good quality insurance and sensible precautions, keeping expensive items out of sight. A Safe lock for spare wheel and not leaving keys hanging around, especially when travelling.