You can read his post and his links to his thoughtful thesis here.
On a related note, I made a number of comments on that thread (scroll down). See for instance, this comment where I explained the difference between "unitarian" and "Unitarian":
I write with the lower case u for a very important reason. Many "unitarians" from the America's Founding era were NOT members of churches that called themselves "Unitarian" in an official denominational sense.
For instance, Thomas Jefferson, the militant unitarian he, never joined a "Unitarian" Church. John Adams, as well, was a "unitarian" since 1750 and claimed his church had a unitarian minister since that time.
However, his "Congregational Church," at that time (1750), was still formally affiliated with a trinitarian creed (and had many trinitarian church members; back then the unitarian preachers tended to keep the unitarian and trinitarian members together by simply refusing to discuss orthodox trinitarian doctrine).
I'm not sure of the exact date that Adams' Congregational Church officially became "Unitarian," but I think it was sometime in the early 19th Century (around the time when Harvard officially became Unitarian).
One thing that makes this (when "unitarianism" becomes "Unitarianism") hard to determine exactly is that U/unitarians are loath to recognize formalities as a matter of theological doctrine!
It's interesting to note, though, that J. Adams' Congregational Church had had a unitarian preacher since 1750, the date Adams claimed he had converted to unitarianism.