Kindle DX is a nifty, if costly, way to carry your library

Avid readers usually have a choice. Read a current hardcover best seller that's heavier to travel with and more expensive. Or lighten the load with a cheaper paperback whose title is dated.

It's an imperfect analogy. But the arrival this week of the larger-screen Amazon amzn Kindle DX means potential customers have a similar decision to make.

At 18.9 ounces, the DX still weighs less and is much thinner than most hardcover books. As with previous Kindles you can cart a whole library. The DX stores up to 3,500 books, compared with 1,500 for its paperback-size sibling, the Kindle 2. But Kindle 2 is about a half-pound lighter. Both models fit into a knapsack with no problem.

There's a weightier consideration: cost. At $489, the DX commands a premium that's hard to justify, especially in this economy. I'm a fan of Kindle 2, but even it is too pricey at $359.

What's more, the students who represent a prime potential market for the DX — Amazon is making a push on college campuses and with textbook publishers — may be cash poor.

Amazon says ardent readers can recoup the cost eventually, because books sold in the wireless Kindle Store are discounted, $9.99 for most best sellers.

It's still mostly unknown, though, what textbook publishers plan to charge. The one I sampled, Biology of Fishes by Richard H. Moore, costs $68.80 in the Kindle Store, down from the $86 digital list price. I'd expect decent price breaks. Physical textbooks are often resold as used books, so publishers get bupkis.

Why consider a Kindle DX? The obvious answer is the larger screen, 9.7 inches. All models are based on the same black-and-white E-Ink technology that does such a fine job of mimicking the experience of reading on paper. But the DX has 2½ times the surface area, making it better suited for textbooks, newspapers and magazines.

Another plus: The DX can handle business and personal documents in the Adobe PDF format; these must be converted before you can read them on Kindle 2.

A closer read:

•What Kindles have in common. The tablet-shaped DX looks a lot like other Kindles. Control buttons (next/previous page, menu, etc.) are to the right, along with the five-way navigational switch found on Kindle 2. Unlike other models, there are no buttons on the left.

As before, you can access the wireless Kindle Store for trying, buying and downloading books in less than a minute. Amazon makes a big deal about not charging for its 3G cellular wireless, but why should they? You're going to spend money, for goodness' sake. But there's no denying the convenience; it's why I prefer Amazon's readers to rivals.

The DX shares other traits with earlier models. You can alter the font size, look up definitions, search within your library, bookmark pages, return to the last page you were reading (even from one Kindle to the next) and annotate text.

The machine also plays MP3s and has a crude Web browser. The Web loses impact without color. So do the periodicals and textbooks you read on the Kindle, and color is still a long way off. The DX also has the read-aloud text-to-speech feature introduced on the Kindle 2.

Amazon says the battery life is roughly the same between the DX and Kindle 2, as well — about four days with wireless on; about two weeks, if off. Displays aren't backlit, so they drain less power than computer screens and don't cause eyestrain. The battery is not removable.

•What's different? The large screen is the obvious answer. You come to appreciate the ability to display more text (or graphics). And I didn't notice any major differences in the speed at which pages refreshed.

PDF files looked fine, too. You can transfer these and other personal or business documents to the Kindle via USB for free, or by e-mailing them to the reader for 15 cents per megabyte.

Turn the DX to its side, and the screen orientation changes from portrait to landscape mode, as an iPhone does. Good thing that you can turn the feature off — I inadvertently rotated pages reading in bed. Rotating the unit is the only way to make PDF fonts bigger. You can also limit the number of words per line of text.

Ever mindful of the cost, Amazon plans to launch pilots this summer with The New York Times, Boston Globe and The Washington Post to offer the DX at a discount to potential subscribers who live where home delivery isn't available. It remains to be seen if such a cellphone-like subsidy will pan out. Amazon is also planning to run trials in the fall at various colleges to distribute DX units to students. No word on price.

Reading on the big screen was generally a pleasure. It's too bad the DX comes with a bulky price.