It may not seem like much, but there is a big difference in the Biblical text between "only begotten son" and "only begotten God". Depending on how this is read, the implications are great, and they are substantive and doctrinal. Tregelles was a man who became enamored of Textual Criticism. (For another example, see the work of Kanamori, and his book available here). Tregelles became a follower of men and of Textual Criticism, and the result of his work was the immense shift away from the historic Greek Text used by the Protestants and the Eastern Orthodox Church for 2000 years, and having Protestant Bible Societies agree to use the historically rejected Codex Vaticanus (advocated and recommended by Westcott, Hort, Nestle, and Tischendorf). Tregelles was a friend of both Hort and Nestle, and encouraged Nestle to talk with the British and Foreign Bible Society leaders between 1900 and 1904. In 1904, the BFBS announced it would abandon its leadership in the use of the Textus Receptus, the Greek Text used by Christians. It was that text which had kept the Church strong and grounded. Now we have many versions, many Greek texts, much confusion and few answers. It would be a sad thing to be Tregelles. This is one article that documents how his translation skills - despite his hopes - left much to be desired. The text is mostly in English.