All mobi page numbers are estimates no matter what device you use. The format does not support page numbers.
Cybook has more font sizes (12) than EZ reader which is 3 I think. EZ reader downloadable trutype fonts do not work on mobi files, only FB2 and text I believe. Complex PDF support in the Cybook is better with better zoom options and panning. The Hanlin readers are much more open and even the OS can be replaced with an open version if you wish.