I agree with everything.
Anime adaptations that leave stuff from the manga out really irritate me, mostly because i can't help but think about how people that do not read the manga won't be able to appreciate the story fully because the director is choosing to stray from the clearly superior source material. The Diana/King/Helbrum stuff was done far better in the Nanatsu no Taizai manga, and i remember the passing of time not only made sense but it was used as a surprise or sorts; because you expected hours and days to have passed only to learn that it had been years and even decades each time you flipped a page..
That being said, i still enjoyed the episode. In fact i am surprised at how much of the entire Nanatsu no Taizai anime is so enjoyable. The fact that i read the manga and know what's going to happen doesn't even bother me. The last few episodes have been really impressive (though the Gowther bits didn't exactly workout). We need more anime like this. I actually look forward to each new episode.