Creator here. I would absolutely agree with this, but let me shed a bit more light to clarify: the underlying idea of B+ trees with inline caches is not patented (or maybe it was, but a long time ago?). Tokutek's patents are all focused on the methods they use to achieve concurrent operations on a single tree--they have a very interesting & novel locking protocol.
The Hitchhiker tree completely avoids their patents, since it makes very different decisions in order to become purely functional.
Great work by the way! Really like the description of the code structure on the README page.
If patent is indeed not an issue, I might play with translating that to Erlang. You already did the hard work and also made it functional. I'd have to learn to read Clojure.
Speaking of functional, I was surprised to find the other day, Erlang's queue module implements an Okasaki API, complete with funny function names like deah, liat, and snoc.
The Hitchhiker tree completely avoids their patents, since it makes very different decisions in order to become purely functional.