The common term a Southerner would use is "damned Yankee" for those who move to the south and stay. Gettin' pretty thick with 'em here in TN, too. They got me surrounded.....
I will say that I try very hard NOT to use the phrase "Back Home we used to do it like......" LOL! I figure that if I want to do it the way it was done back home, then I can go back there. When in Rome, etc etc.
But, I'll let you in on a secret...Mainers (the "natives" at least) don't especially like folks from Boston, NY, NJ, either. The running joke up there is that Maine split from Massachusetts in 1820, and Boston has been buying the state back, one house lot at a time.