Earlier quoted context omitted.
I find that an eInk Kindle is "close enough" to a paper book in terms of immersion for me. But reading on my iPad (or even worse, computer) definitely is not. I get notifications, there's always the temptation to jump out and "just check email," etc. With the Kindle there is no distraction, and for me that seems to be more important than the tactile experience of a printed book (though I do still enjoy printed books)…
Personally I've found that the loss of one spatial dimension in the transition from paper to ebook actually makes the book less engaging and more difficult to retain details. I think (again, my personal experience) that reading while also having a tactile sense of where I am in the book (say ~20% of the way through) makes it easier to remember smaller details; perhaps the physical book helps my brain create a sort of…
Maybe it'll become feasible as the price for flexible eink displays drops.