"In fact, it's probably safer since it's so much larger it takes less of a glance to obtain the information."
Just the opposite, actually. The larger screen of the laptop actually makes it more difficult, and therefor more time consuming, to zero in with the eyes to obtain the information you want. Your eyes have to find the screen itself, then zero in on the few square inches of the screen in which your information is contained. You look at the map, then zero in on where on the map you are, then you have to look in another area for other information like distance and time to next turn, what the next turn is, etc.
All of that information is available, at a glance, in the same little 4" square, with a standalone GPS unit.
The military has found that the more information you need to display on a screen, the smaller the screen the better. They also found that teams with smaller, individual CRT's perform much better, and react far quicker, than when using a single, large display. Video gamers, especially the games that require quick reactions, score far higher on smaller screens than on larger screens.
It's all a matter of how far you are positioned away from the screen, and how the eyes and stereo vision work. At arm's length you can see pretty much everything in detail in an area just about the size of your fist (not coincidentally, about 4 square inches). If you hold out your arm and point your fist at your laptop monitor, knuckles pointed at the monitor, if your fist doesn't completely cover the screen, it's too close for you to readily see and comprehend all of the information on the screen in a single glance. Any part of the screen that you can see on either side of your fist is a part of the screen that you must re-focus on in order to see it.
I guarantee you, the myth of the big screen is a Green Eggs and Ham thing. Fact is, [FONT=Verdana, Arial, Helvetica, sans-serif][SIZE=-1]it is much easier to perform most tasks when you can take in more information at a single glance.
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