One reason why I took the approach of following topics and users, rather than subhubs, is that some of the most interesting submissions might only qualify for a hub with very few readers, which is a problem I've encountered with /r/. Here, you can construct a feed in a way similar to the reddit custom frontpage, but you can choose to follow people as well as topics themselves. Thanks again for the thoughts.
-It's too bad this fell off the new page so fast. Maybe I'll try again in a few weeks after some more work. Maybe at a slower time of day too.