I can think of a great reason why this system is wonderful, even for people in less harsh environments than Andy lists. People like us who have access to computers but who may be away on vacation for a while or traveling for business.
Reading from the memory stick or SD card, when there are lots of books on them, is slower than if the books are in the main memory of the Reader. So carrying around reference works as well as entertainment reading on memory cards isn't nearly as efficient as it will someday hopefully be.
So this system of using a carrying device so that you can transfer one or two books to the memory card for reading, thus not slowing down the Reader, seems to me to be wonderful.
On the 500 especially -- I found that even having 100 books or so on my memory stick slowed things down to where it would take a few seconds to place a bookmark and it would take almost 30 to 45 seconds when i turned the reader on before I could really start reading with almost normal-speed page turns. so now I keep a single mutli-MB reference on the memory stick and all the other reading books in the main memory of my 500.
I will certainly be investigating using such a library-carrying device for vacation or business travel. Unfortunately my Epson P2000 only works for picture files and mp3 files. Boo hoo!
