I must admit that I don't really see how pitlocks can prevent a bike from being stolen although it would make its resale that much lower if the person who buys it from the thief can't remove the wheels or other components for maintenance. I suppose that if you used the appropriate tool to remove the front wheel from the bike and locked it beside the bike, without the tool, the front wheel couldn't be re-installed but other than that, the pitlock doesn't really seem to be much of a deterrent.

I agree with the double lock strategy but I don't live in an area with a lot of theft so I can get away with a decent U-lock to an immovable object. I'd use the U-lock through the rear wheel/frame to the object and then a cable (either a combination cable or cable plus padlock) through the front wheel/frame and the object again or just the front wheel/frame. My seat is not an expensive model so I don't need it locked nor do I feel that I need to remove the seatpost.