Well, I don't have any DRM books
For the same reason I don't have any DRM music; I rip music from CDs I've bought and I scan and OCR books from books I own. Epub for the Sony Pocket (PRS-300) has a perfectly good display, thank you, recharges once a month, and holds five hundred books.
While I have the choice I will not download either music or books.
To be honest it wouldn't even occur to me to read a book on the computer (except for proof-reading and preparation) or on an ipad or similar (even if I owned one).