My theft deterrent is that I would beat the living S**t out of anyone who touches it!.
I am of Calabrian descent, and everyone in my area knows it.
I have had a few charges for assault, and locals know to leave me, my stuff, and my family alone.
Of course it helps that a few 'patched' members from my past come to visit from time to time. They are highly visible.
Of course, it is also insured, so ... whatever.