I don't think this is true any more. I've checked the manual for the 700 series Nuvis (I've got a 770) and multiple via points are permitted.The only issue, aside from arranging power and audio should you need them, is that all but the top end Nuvis only do point to point navigation. You set the destination and the device decides how you get there (OK you can set fastest, shortest etc.). You can add one via point, to visit along the way, but that's it.
