[wingmongyee]

I found when switching from my Sony reader to the Kobo Glo HD a couple of years ago that when reading epubs on the Kobo, the reader felt sluggish, i.e. slow page turns, etc, compare to the Sony reader. When the epubs were converted to kepub however, the Glo HD felt as responsive as the Sony, so I installed the Kobo Touch Extended driver plugin in Calibre and ever since, all the epubs I transfer to the Kobo are converted to kepub on the fly. My calibre library remains in epub.

Because of my experience, I think it's preferable to use kepub with a kobo reader.

Having said that, my experience with epub being sluggish on the Kobo reader is two years old, and it could be that the multiple firmware updates that were made since have fix the problem. Anyway, converting to Kepub on the fly with Calibre and the Kobo driver plugin takes hardly any more time than transferring a book without converting it, and the reading experience is excellent.

(Also, if I remember well, the reader wouldn't see the chapters when in epub format, in kepub it does and so you can see how long you have left until the end of the chapter, which is a feature I love).