I embarrassed myself as a Noogler trying to explain what in my head seemed like a good tradeoff between hash size (also of URIs) and collision handling. The process had fixed storage for a table of known hashes, and every collision was tested for validity before taking action. If you could use a truncated hash, you’d obviously increase your collisions, but if you’re going to validate all collisions anyway, it seemed like you could increase your coverage substantially (in the 60-bit case it would have been 4x) while only marginally increasing your overhead of collision handling.

There's some kind of sparsity/entropy function involved with optimizing these two but I'm too clueless to sort it out. Without the vocabulary to make my case I just got weirded out by a bunch of smart people staring at me quizzically. Sooo..