(Actually....how many of the characters on DS ever had the right Maine accent )
I have lived in Maine for 15 years and have met very few people with the classic Maine accent. The first time I heard it was from a comedian named Tim Samples and he only uses it during his act. The accent I hear the most is French-Canadian. I was told that people who attempt to imitate the Maine accent always over do it. It always has a lovely lilt when done by a local.
As for the southern accent, I remember the mini-series "North and South" and some of the actors sounded ridiculous. My father is a native of Texas and it irritates him that in the movies all southerners sound alike regardless of where they came from. However, my mother said my father sounded just like Gomer Pyle when she first met him. He has very little accent left after living in California for 60+ years.
I hope the new series decides not to use a Maine accent or it will sound like "Murder She Wrote"