I don't know of a connection between the Maine Donnells and those in Guilford Co., NC but there has been a connection established between the Cecil Co., MD Donnells and Guilford Co.
My mother was a Donnel (with 1 L).Our earliest proven ancestor was John Donnel, found on the 1772 tax list in Northumberland Co., PA.Some data suggests he was earlier in Northampton Co., PA but Northumberland was taken from Northampton, so he may just have been in the same location earlier.There were settlements in that area as early as the late 1740s.
He may have been part of the Cecil Co. Donnells.His wife was Mary Fleming of the Chester Co., PA Flemings, originating with William Fleming and Mary Moore.
We've had a direct line descendant from our John Donnel tested (he spells his name Donnell), although I think we used Donnel at FTDNA, where you can check his haplogroup I2b1a and his pedigree.You can also find more about Clan Donald athttp://dna-project.clan-donald-usa.org:80/http://dna-project.clan-donald-usa.org:80/
The thing about all the Donnells is that they stayed with the same given names.Our John had sons Henry, John, Jonathan, William, Robert, James and Samuel and daughters Margaret and Elizabeth.These pretty well follow the names for the ME, MD and NC families.