I was contemplating a system too......
I have learned that pretty much anything just keeps the honest people honest and will only slow down a thief a bit....if they want it they will get it.
Remote battery alarms are neat, but a lot of wiring, wouldnt it be?
The removable sterring wheel is a neat idea too, but then the thief can just flat bed it away.
For now I have a couple of the usual tactics....will at least keep the joy riders away I hope.....and decent insurance coverage "just in case" though it would break my heart.
I recently had, of all things, a motorcycle helmet stolen off my bike.....it was cable-locked to the bike.
Someone cut the cable to get it.
A 4 year old helmet, far from being new.
If someone will do that for an old helmet, what do you think someone will do to get a gorgeous classic car if they want it?
I think most of the "anti theft devices" these days are more or less for peace of mind of the owner even if not fully effective.
Although the lojack system is cool....at least you have a chance at finding the car eventually.