Nice post. I used only Kindle for several years. It is cheaper and faster. But I started to notice that I did not learn as much when I read on Kindle, and I did not get that emotional invested that I did in a real book. Story short, I do not use Kindle anymore, and only buy real books. Now I find it fun reading again, I learn more, and I also love the smell of the real thing. Just my personal opinion. Perhaps I'll change back to Kindle again. Takes at least 2 weeks (or more) to get my books from Amazon to Norway. I could certainly save myself for a lot of money too.
You know, now that you mention it I can totally see how I maybe retain less than I would in the past with normal books. It's interesting. I must keep an eye on this and see what happens. Thank you for your comment and insight!