Author here, thanks for the feedback! Just to be clear, are you suggesting that I be more explicit in the documentation about the differences between the default router and Expresso? I have a "Migration" section, but it could be expanded and renamed.
I built a similarly simple feed aggregator for anyone to use at https://plumfeed.com Shows the most recent post of each feed. I've found it particularly nice for blogs and comics that update once a day or less.
Another direction you can go with this is to make a series of Git puzzles. Basically, starting with this diagram A, convert to diagram B in the least number of moves. To be extra useful, these could revolve around common Git pitfalls.