Got it! I ordered and received a copy of the article mentioned by John S.:
Joan A. Hunter, "William Holton of Hartford, Connecticut and Northampton, Massachusetts: With Discussion of his Prior History and Probable English Origin," in The Genealogist, vol. 25, no. 1 (Spring 2011), pp. 3-28.
It's later than Anderson (William Haulton is profiled in GM3, 2003) and the American Society of Genealogists I believe y'all said is a reliable/high-quality source, so it merits consideration for PGM. Here are the relevant conclusions:
- William Holton who sailed from Ipswich on the Francis 1634 was probably the William Holton baptized at Nayland 1610, son of Edward Holton (mother not recorded).
- There were two Edward Holtons in Nayland of the appropriate age; William was probably the son of Edward bap. 1570, son of John, who m. Constance Adkinson 1598.
Regarding the above, "No evidence was found that would disprove this identification, but it cannot be regarded as fully proven."
- William Holton of the Francis probably settled in Newtown (Cambridge) upon arrival, though he is absent from records there.
- William Holton of the Francis definitely owned land in Hartford by 1640, and was probably one of the original settlers around 1636.
William Holton of Hartford was already known to have migrated to Northampton in May 1653.
The author cites Nayland records; the passenger lists of the Francis and the Elizabeth (which sailed together from Ipswich); research performed in 1937 by Suffolk genealogist Lilian J. Redstone; Hartford land records, in which she demonstrates a few errors and omissions by Anderson; and movements of allied families from Nayland to Newtown to Hartford which William Holton may have paralleled.
Finally, William Holton's wife, Mary, is still thoroughly unknown and is definitely not Mary Winche.
It looks pretty good. What say you, PGM? :)