This won't be a problem for most people, since they read stuff written by Dan Brown that really doesn't require a rereading 20 years down the line. But I understand the sentiment.

Nonetheless my understanding is you can fairly easily get any pdf onto the Kindle, meaning if you get a non-DRMed version of the books you're fine. Is that not correct? I own a number of digital music player's that support one DRM scheme or another, and use them frequently, yet have never actually purchased a DRM'ed file.