Now I have found a recent one: a Pentecostal church in Oklahoma that has merged into a Unitarian Universalist congregation at Tulsa, Oklahoma.
It seems that its Bishop Pearson was an outcast in the Pentecostal world because of his social inclusivism. This describes the problem:
Pearson had been a longstanding associate of The Joint College of African American Pentecostal Bishops Congress, who has deemed him "heretical" for preaching a Gospel that included everyone and excluded no one. Several other evangelicals issued harsh press releases and statements distancing themselves from Pearson, many of whom had been given their very first chances at national exposure through Pearson's ministry.
It seems that after some time, and with losses, Pearson took on an inclusive universalist theology. He faced reaction from Oral Roberts University and presumably from ASUZA (Pentecostal gathering) as well, and he was involved in both. He has been an influential black church minister, with appearances on national media, and has pursued a social gospel, inclusivity, diversity and connections between faith groups. Pearson and his family moved to the Unitarians first to make it his church, and then encouraged his New Dimensions Pentacostals to move there, where the inclusivism of his congregation would be supported. The result has been to make the Unitarian worship change and become more lively.
American denominational religion has always been more flexible than in the United Kingdom, but I noticed when looking at the history of the Hull Unitarian church how it absorbed the Baptist churches that went Unitarian (three Hull Unitarian-leaning Baptist congregations merged, it then moved over) and it co-operated with a sympathetic Congregationalist church during the Second World War. It is easier for independent congregations to change. Beyond that, it is individuals who move in different directions. I know of now an Essex based priest west of the M11 who was a Unitarian minister (one of his churches has become an ecumenical centre), just as I was assisted by and stayed with a Unitarian minister who had been an Anglican priest. The history of the Broad Church movement of the Church of England includes co-operation and crossing in both directions in the nineteenth century.
Still, in the context of The Episcopal Church, there is no evidence whatsoever of any movement there that would see it being compatible with Unitarianism: does anyone in TEC even discuss with sympathy and involvement W. E. Channing (for example - he would be the first port of call) that has any institutional impact? Will there be any more Kings Chapels, as at Boston? This present day slur is just a fantasy of hard-right evangelicals.
I see that most of Pittsburgh has decided to separate and go elsewhere, so TEC will have to reconstitute the diocese from what is left and presumably recover what is taken, if that is expedient. This statement, made after the vote, by Presiding Bishop Katherine Jefferts Schori is hardly 'Unitarian':
"The mission of God, in which The Episcopal Church participates, is to love God and to love our neighbors as ourselves. We cannot do one without doing the other. We believe that it is in serving the least among us that we discover the image of God, and the presence of a suffering Christ. It is in serving those least that we rediscover our common mission, which transcends our differences. Jesus weeps at the bickering of his brothers and sisters, particularly when they miss him in their midst."