Hi James!
I am the current maintainer of the latest versions of the Onyx firmware. It is completely supported and not EOL at all :) And you are right, the current firmware (12.30) is much more advanced. Battery life is now excellent, there are a lot more features, etc.
Sorry for the links on the documentation being outdated due to a server migration... What operating system are you using? I can send you links to the correct firmware and update software directly,
Ed