does the tom tom automatically recalculate routes if you miss a turn or go the wrong way? i have been looking at the garmin nuvi 660 but thought i'd keep my options open. what do you think about each of them? which one is better? not necessarily which one has more features, just which has a better navigational system? i would be using it at work, on an ambulance, so i can't afford to have it mess up or anything. and i'd rather have the better one.