I've given the unit to my parents and put it permanently in their car. To help with the GPS theft issue, I mounted it low next to the gear shift (not on the windshield where they say the thieves look), and for a simple fix, just tell them to put a baseball cap over it whenever they leave the car. As soon as it's covered up it's very inconspicuous.
Like the baseball cap idea!
My car has NO flat surface to adhere the suction cup thingie, so I recently got some velcro adhesive strips from Michael's and mounted the cradle for the 3.5 version in front of my tach (I can still see the high numbers!) and it's much easier than trying to read it when it was mounted on the console between the seats. I'm pleased but still take it out of the cradle and put it in sleep mode when I leave the car. It's easy to remove and replace.