I'm curious about how this article might be expanded to include the sort of Congregationalism that was characteristic of German Lutheranism and German Lutheran bodies in the United States. In German Lutheran style congregationalism, there seems to be the independence of the local church characteristic of English Puritan style congregationalism, but without necessarily the same theological rationale. Also, German Lutheran style congregationalism was/is much more clergy-centric than Purtian style congregationalism.
I don't know all the details necessarily to write this material myself, but think it might be a good rounding out of this article--it is still a form of congregationalist church governance, but somewhat different from that described already.