I'll be a while going through this.
I was thinking about our earlier discussion where I was hammering on
the point that compressing entropy too early is a mistake, and just
now realized that I should have given you credit for my recent 4.7-rc1
patch 2a18da7a. The hash function ("good, fast AND cheap!") introduced
there exploits that point: using a larger hash state (and postponing
compression to the final size) dramatically reduces the requirements on
the hash mixing function.
I wasn't conscious of it at the time, but I just now realized that
explaining it clarified the point in my mind, which led to applying
the principle in other situations.
So thank you!