Hi,
I have McGregor ancestors, and their surnames were all over the place, as explained above. However, in that Highland area it was also common to use sept names, and spell them in several different ways. This appeareed to be true for most families, but the one I know in detail is my own, which was Campbell. That was rearly used, instead they also used; McAinsh, McTavish, McKaush, McAwish, Aunsh, McAnsh, McAuish. I suspect they always said it the same way, but the different spellings are how the minister interpreted what he had heard.
John.