To be honest I'd rather have a standard one and run the risk. The damage some scrote could do trying to remove an anti-theft aerial wouldn't be worth the inconvenience!
Fooking hell, the aerials just unscrew. If i dont garage my car overnight i remover the areial and put it in the car. 20 second job. Either move to another area, or remove the aerial. Its easy.
NIK the anti theft ones dont work with the Clio connection, as the screw fixing is a female on the car therefore the little grub screw that locks into place, is no use what so ever.
I am with Stromba on this one (Shit did i really say that :lol if the car is left outside take the aerial off a pop it in the boot, i do that whenever i am somewhere i am not sure about.