Various Models' features

I have a TomTom One 3rd edition GPS. It was on sale for $150.00.

What I am interested in knowing is - what are the features that make other higher costing models worth 3 times as much? This one shows me where I am, tells me how to get from point A to point B, lists POIs etc.
If I were to get a new GPS next year, why should I get one of the more expensive ones?

I know that you can get GPS systems with larger screens and ones that will tell you the name of the street.

Do the more expensive ones have better maps or more accurate GPS technology?

Better maps? Slightly. I have seen comparisons between the USA_Canada maps and the NA maps. The NA maps include more tertiary and private roads, and have greater geographical detail. I think you can't beat the ONE series as far as bang for your buck. That's why it's a Consumer Reports best buy. You just have to decide if text to speech, slightly better maps, mp3 players, phone dialers, etc are worth hundreds more dollars to you.

Well there are a few other things too. The 720 and 920 have faster CPU's, more RAM (for internal program use) as well as more internal storage. The 720 and 920 also allow you to turn off autozoom.

Check out this feature matrix. It should answer most of your questions about the difference between models: http://www.pocketgpsworld.com/navcor...n_20071121.php