I bought a Sony eReader some years ago and it is very good for travel reading. An example of the +s I was waiting to read the last part of the Millenium trilogy of Stig Larsen, it was due to be published in pb on the day I was flying to the Getaway!, I could NOT get it in advance but found that I could buy a copy of the "airport edition" at Heatrow, My eReader weighs about 350g and at that time held 200+ books including the tech manuals for my Edirol recorder Both my Cameras, (in PDF) complete with b/w pics and diagrams. The pb when I bought weiged about 1.2 Kg for a SINGLE book.
My eReader has insertable memory (the Kindle does not) amd takes SDHC cards and Memory sticks as large as you like, a 4Gb SD cards Holds a HELL of a lot of text ( and I am sure you could get the wHOLE of the DT on one or 2 of sufficient size. It means you can have seperate librarys on different cards,
OK a draw back is the Sony "mystification" stuff with activation but that is just a chore.
You can Recharge it from the USB connector on your computer or laptop or from the mains.
You can load any TEXT docs from you computer, either as text or as PDFs so if you have a draft of your PhD thesis to correct or just a collection of docs. you can have then in easily carried format.
Project Gutenberg has a lot of "out of Copywrite" stuff available for download (I found ALL the Thorne Smith books there, and lots of Kipling and other writers I like for travel reading)all FREE.
I Love Real Books too but HATE lugging them on and off planes and when travelling adding several Kg to my Carry-on bag then only having a small choice for all that weight.
i would not be without mine, and I would say my experience includes a 3 weeks 20,000 mile journey by plane ,train and bus with it as my main source of reading.
You would have to weigh the +s of the different kinds of reader to your personal needs, But they are Just another tool and No one is a universal Panacea. Good Luck