I've done pretty much this for the few e-books I've bought. None of the e-book applications for OS X do proper justification with automatic hyphenation, and some of them (such as B&N's eReader) don't even use subpixel antialiasing. The DRM is generally pretty weak, and it only takes a few regexes to convert them in to valid LaTeX code. After you clean it up a bit and add the semantic markup necessary to get proper chapter divisions, etc., you get a PDF that's a true book, suitable for printing, with typography that is actually readable.