I'm now another year into Auten genealogy (I can even spell it now...) and always come back to your question about the origin of the surname.
I really feel that your suggestion of Aalten being the family origin makes perfect sense of a collection of question marks.
Just to add to your annecdotal 'data', my great Aunt, Nellie Auten b. 1902 told us that she was told the name came about from 'a dutch boy (Adriaen Hendrickse) married to an english girl (Elizabeth Thomas) who persuaded him to drop the extra 'a' from his name (Aaten) and to use the name ATEN - which he did'.
He most likely came from Holland in about 1651 and was known as Adriaen Hendrickse van Aalten.How easy was it to then become simply A.H. Aaten...Aten.
I wonder how we could ever find out any sort of 'proof'.I live in France and am tempted to try a trip to Aalten one day.