Living on the small island of England, I get away with one CD for the whole country!
I spend a lot of time in the country, and on average use the unit once every 4 driving days, if not more frequently.
Yes, and having spoken to taxi drivers, they agree with me that if you are driving a familiar route, you can normally do better than the nav. unit, but if you have no idea where you're going, use the nav. system!
It's useful for routing round traffic-jams too.
Rumour has it that a new system built into mobile telephones will be available soon - any version that is removable has the advantage of being less stealable.... assuming you take it out of your car!
The only disadvantage to a street pilot that I can think of (only seen specs but never tested it) would be...
No voice guidance, limited route recalculation, AFAIK you have to program your route in advance and load it into the machine.... Is it as accurate as an in-car system which has a gyroscope and hookup to your speedo pulse cable?
I bought an aftermarket as it means I can move it to a new car... in the UK, I have been told the theory is that you never recoup the expenditure on accessories at resale time in any case.
J.