I suspect you're right and was already having similar thoughts regarding the hashing scheme. I put a patch together and am going to supplement with some additional tests of the collision space.

Unordered hashes made more sense for arbitrary Clojure data structures where the keys might be complex compound objects, but once we're in the land of datoms with finite value data types it's pretty easy to enforce a consistent ordering.

(disclaimer: I wrote much of the feature and post)