Anti-theft system, effectiveness?

So I'm wondering if anyone has any information on BMW's anti theft system? Just how effective it is, etc.? I'm wondering if I need to bother using a "club" on my new Z4. It's my opinion that a professional car thief can defeat anything if they apply themselves. But if anyone's going to get a anti-theft system right, my guess is it would be the Germans.

Now I know a thief could easily defeat a club, but it would be one more layer that they have to get through.

'The Club' is great for 'part time', 'opportunity', would be thiefs but as you said, if they want something........the good thing is, they won't be driving your car away without removing a number of panels and changing out the DME and EWS control units with prematched ones and holding a matching key to the antenna ring of the ignition tumbler they've broken out first to steer the car. That's a lot of work for anybody and your right I think, BMW at least has the closest to a real 'Anti-Theft' system I know of though are sure there are others.