Here's another minor issue--or maybe it's just a question. Another writer sent me her manuscript to read in RTF format, and I didn't like the way my PRS700 displayed it in terms of font size and spacing, so I converted it to EPUB. That made it much more readable in terms of font, but all the vertical (blank) line spacing disappeared, so chapters are squished together, etc. It's okay for my immediate purpose, but I wonder why it happened.
I've encountered the same problem in Mobi Creator with my own files, but not to such an extreme.