I like the 10 postings per "river". But:
1) Click on feed with more than 10 items.
2) Use space bar to page down and read through everything.
3) Continue to hit space bar because you are skimming
You suddenly find yourself in single item view mode. If you were looking at a river of news for a catagory, then you may find yourself looking at a different blog.
-> Make the space bar do the equiv of the "next" button that appears at the bottom.
-> Retrain us to use another button the scroll (like the page down, etc.) that will then take us to the next 10 items.
-> Come up with some other brilliant way to make this as fast as reading through all 1000 posts at once. ;-)