So I just signed up for this and Blinkist to compare. I listened to Deep Work by Cal Newport, first on Headway then on Blinkist. The Headway was 15 minutes and the Blinkist was 9. It is hard to gauge which is most beneficial, as the second listen's effectiveness benefits from the first. But I do like that Headway could fit in some more content in those extra minutes.

One thing like more about Blinkist is that another read automatically started playing. I don't think Headway did this. Also Blinkist has a queue, where you can make a playlist and it will continuously play. This is a very important feature for me, as I would like to set it and forget it while walking or driving. I really home Headway will add this functionality.