Re: Zone - I'm not distracted by changing pages anymore. Just an unconscious muscle twitch and (with newer kindles, and all iPads), I'm onto the next page. I've had many a 12+ hour reading sessions, and several "Get sucked into a book" weekends with digital texts.
Volatility - My books are in the Amazon Cloud. All of my digital books are still available to me. 100%. I have access to about 5% of the paper books I've purchased in my life. The _worst_ case scenario, is that Digital Books become as Volatile as paper books, if Amazon.com goes out of business, and I'm stuck with (horrors) the physical representation of the book as present on my kindle/iPad (and Laptop backup, and back blaze backup of my Laptop).
The cloud changes everything for volatility.
DRM Sucks. Big Time. With that said, Amazon's implementation only impact is that I don't casually lend books to other - which I typically never have anyways, so no impact on me. I too like (and frequently take use) of the fact that 100% of my books are available on my Kindle, iPad, iPhone, Laptop, and CloudReader.
But - with that said - the DRM on physical books is pretty harsh too - You need to go to a photocopier to make a copy of the book. I just lend my mother my cloud reader account, and she can read any of my books on the web. Or lend a second friend my Kindle, and voila - he has all of my books. While I still have all of them on my iPad and iPhone. Or, if I don't have five lent out, I can pull them onto my old K2.
I don't think DRM on the kindle has ever stopped me from reading, or lending a book to someone I know. It _does_ prevent casual lending. Agreed there.
I haven't read a paper book in about 4 years. I find it bizarre to even consider moving back to them.