Practically speaking it matters not. Calibre can do pretty lossless (practically speaking) conversions between formats. The limitations/features of ebook reader

Practically speaking it matters not. Calibre can do pretty lossless (practically speaking) conversions between formats. The limitations/features of ebook readers have a much greater influence on how a book looks than the format. I love the status-quo where Amazon pretends that their DRM is not hopelessly compromised and I get to strip the DRM from the vast quantities of ebooks I purchase there. I would much rather they keep turning this blind eye than adopt epub behind a more effective DRM scheme. That would be a huge loss to me. When my e-ink kindle can support high-resolution color images, smooth and fast LCD-like scrolling etc. then I might care about epub features, but while I don't want or expect more from my kindle than a paperback, I am quite happy.