This is exactly the same for me. I definitely like being able to switch between a tablet/e-reader for regular reading and using my phone when I'm stuck waiting in line or transport.

I don't specifically need the physical book; space-wise it'd be difficult to keep all of the books I'd like to own. Just not enough space. That means that DRM becomes a major concern; I have absolutely no issue with stripping DRM for my own use whether it's a game, movie, music, or book.