i had no idea this was even an option for the 460
i will say, the nav comes in handy when you are way off the beaten path or in BF nowhere and need GPS but dont have phone signal.
also, you get used to the screen controls pretty quickly. i would prefer a more functional, simpler, manual control stack - but the touch screen is really not that bad.
with that being said - saving 3 grand sounds cool. but that will also probably bite you in resale since the folks looking for a non-nav version will be pretty slim.