Here is the link to Nathan's written review comparing the Aura to the Kindle Paperwhite:
http://blog.the-ebook-reader.com/201...-review-video/.
It is not epub vs kepub, or Aura vs Glo, or even Aura vs Sony that matters, but Aura vs Kindle Paperwhite, Kobo's main competitor. If I was the Aura product manager, I would be worried. "What do you mean, our flagship reader, with the biggest screen yet, shows less text than the Kindle?" Fortunately for Kobo this is a software problem and not a hardware problem. The hardware is great, the software is...improving and can be made better than the Kindle.
Regarding paragraph spacing (white space between paragraphs). I prefer to remove this myself (using Sigil), and would not trust code (Calibre, Kobo firmware etc) to do it. It is simple enough to set margin-top and margin-bottom to 0 on p elements, but this affects
all paragraphs, not just the main body text. You end up with scrunched up table of contents, headings, title pages etc, which does not look pretty.
The trick is to only adjust/remove these margins for body text paragraphs, but these can be difficult to identify programmatically (I know, because I have tried with mixed success). It is personal preference as to how big a margin to allow between paragraphs: 1 line, half a line, none?
Also some paragraphs do not use p elements (divs etc). Once you remove the margin, you have to have a text-indent, but probably not on the first paragraph in a section/chapter. How big should the text-indent be (another personal preference)? It soon gets rather complicated.