I would like to see you access a Truecrypt encrypted drive with dual encryption and boot password after is has been powered down when law enforcement could not do it.
As far as the hard drive encryption. Try it on a laptop, remove it and see if you can access it on another machine. You can't do it with linux. It may possible to remove the encryption with hardware, a lot of money and a clean room but this isn't something the average thief is going to have access to. Maybe I am wrong. Please PM me and tell me how you would do it.