I DID buy mine from Troy mostly for the extra pece of mind. Hopefully I wil not need it very often, as the Prius Is rated vey dependable. I only have 5300 miles so far, so I can't really say much about if I will end up using enough to pay for it or not.

I DO Have an ongoing Navigation System Quirk whereby I cannot input my home street as it cannot see it, even though this subdivision is 15 years old.
My dealer has an open ticket on the Nav system. I reported the mising street to Navteq.

Hopefully becaue this abnormality is an ongoing thing, seemingly without any type of a solution, my dealer will have to supply me with an update disc free. Let's hope that's true.

You need to look at this objectively and make your decsion based on affordability for you.

Good Luck, Robert